Algebra word problem - please help!?

Assume that earlier grade was 'x'

if it increased by 20% that means it is 1.2x now

1.2x = 90

solve for x and it gives x = 75

Grade in previous marking period = 75

If the students current grade is a 90% then we’re of course assuming it’s out of 100%

90/100

Now since the students grade improved 20% from the last grading period then you add that to the previous 100% giving you

90/ 120 = .75

And since grades are in percentages you multiply .75 by 100 giving you

75% as the students previous grade

Variable:

x = previous grade

Given: A student's grade improved 20% over the grade for the precious marking period, and the current grade is 90.

Means: x + 0.2x = 90

Solve.

x + 0.2x = 90

1.2x = 90

x = 90 / 1.2

x = 75

If the grade has improved by 20%, and the current grade is 90, then 90 must be 120% of the original grade.

Therfore, take 90 and divide by 120 = 0.75.

This gives you what 1% of the real mark is.

Then times by 100 to get the previous mark

0.75 * 100 =75

Hope that helps

if the student's grade improved by 20% over the last grading period and his grade now is 90%, we could make the following statement about his earlier grade: Grade now = grade earlier + 20%* grade earlier, or in symbols

G(n) =90 =G(e)*(1.+.2) using decimals instead of percents

solving for G(e) = 90/(1.2)= 75

Percent improvement is measured from the original value.

If 90 is a 20% improvement over the original grade, then we have that

x + .2*x = 90

1.2x = 90

x = 90/1.2 = 75

Check: improvement from 75 to 90 is 15/75 * 100 pct = 20 pct

90 x 100/120

= 75

for questions like these all you have to do is read the sentence and make a formula. i know that for beginners it may not be as easy as it sounds but i'll show you step by step: The Randolphs used 12 more gal of fuel oil in October than in September: From this you know that they used more gas in october than september right? and that they used 12 gal more in october. so: if i let septembers gas be x gal therefore: octobers gas will be 12 gal more = (x + 12)gal if youre wondering how the hell i knew to name september x gal and not october, to be honest it doesnt matter. let's see what happens if its the other way round. if october is = x gal then: september will be 12 gal lesser than october = (x - 12)gal so you see? it really doesnt matter. as long as you clearly state what is your x and work from there and not stray, you cannot go wrong. and the reason i chose to make september x is becasue i prefer working with (x + 12) then (x - 12). : ) moving on... so youve settled october: (x +12) gal september: (x) gal now for the seond part of the sentence: and twice as much oil in November as in September. this is relatively straightforward now that you already know that september is x gal. since november is twice as more as september: november's gas = 2x gal so now you know: september: x gal october: x + 12 gal november: 2x gal the next sentence is: If they used 132 gal for the 3 months, how much was used during each month? now this is easy. since they used 132 gal for 3 months, it tells you that the TOTAL consumption for the 3 months would be equal to 132 gal. hence, x + (x + 12) + 2x = 132 bringing the 12 over: x + x + 2x = 132 - 12 4x = 120 x = 30 Now that youve got x and you know the amount of gas used in each month in terms of x, all you have to do is substitute x = 30 into them and you've got your answers! i hope this made you understand algebra a little bit more. Just remember to read and UNDERSTAND what's going on in the question. Name your unkown and stick to it! Write down your needed equations in terms of your unknown and you should have no problem! Have fun with math.

75

Let

G = grade for the previous marking period

G + 0.20G = 90

1.20G = 90

G = 75 --- this is the student's grade for the previous marking period.