Algebra help please!?

Let the amount of money with A is $ X

then the amount of money with B is $ 100+X

Interest Earned By A is $105

That is

7% of X = $105

X= ($105*100)/7

X=$1605

A = B + 100 <- 100 more into account A than account B

a = p ( 1+r/n)^nt n is the number of compounds per year, r is interest rate and p is principle. t is time in years. Filling in that formula we get:

A+105=A(1.07)^t - A will grow by 105 when it earns interest at 7% (1.07) over some time

B+80=B(1.05)^t - B will grow by 80 when it earns interest over some time (same variable, same time) at 5^ (1.05)

solve({A+100=B,A+105=A(1.07)^t,

B+80=B(1.05)^t})

The stupid thing took out half of my solve, presuming it was evil, I guess. I'm editing, I'll fold it.. This is the right way to do it, you *should* use the interest formula, not just multiply by 1.07 - and I believe that these are actually the right answers.

Anyway, In other words, A will have 105 dollars more at 7%, and B will grow (B+80) at 1.05, or 5%

We know that time is supposed to be equal but we don't care what it is, and we are not compounding. We get this answer from that system of 3 equations:

(A=1499.9999999998274, B=1599.9999999998274, t=1.0000000000001)

Rounding, A started with 1500, B started with 1600, and this all happened in 1 year.

(A=1500, B=1600, t=1)

Let the amount invested in Account A be x $

And amount invested in Account B be ( x+ 100) $

Interest earned in Account A = 7/100 X x = 0.07x = 105

x = 10500/7 = 1500 $

Interest earned in Account B = 0.05 ( x + 100) = 80

0.05x + 5 = 80

0.05x = 75

x = 75 /.05 = 1500 $

ANSWER Account A = 1500 $ Account B = 1600 $

CHECK

1500 X 7/100 = 105$

1600 X 5/100 = 80 $

You have to create the equations first. A= account A. B = account B

A+$100=B

Then you can find the original values. $105 is 7% of what number? 105/.07 =$1500.

therefore. A was originally $1500. You don't even need to use the interest earned in B. just add $100 to A.

A=1500

B=1600

Ok so lets use x for the money

So if he put x in account A, he put x+100 in account B.

Account A

x(.07)=105

x=1500

Account B

(x+100)(.05)=80

.05x+5=80

x=1500

So we got x=1500 from both equations so we know we are right.

That means in account A he put 1500 and in account B he put 1600