A person writes all the natural numbers from 100 to 999.?

Count occurrences of the digits 0, 5 and 8 in each possible position.

For each following case the _ indicate spaces which may take values as follows: The hundreds digit may take natural numbers 1-9 inclusive (9 possibilities) whereas the tens and units may take natural numbers 0-9 inclusive (10 possibilities).

For 0:

_ _ 0 -------- 9*10

_ 0 _ -------- 9*10

x = 2*9*10 = 180

for 5:

_ _ 5 --------- 9*10

_ 5 _ --------- 9*10

5 _ _ --------- 10*10

the same for 8s:

y = z = 2*9*10 + 10*10 = 280

2x+2z-3y = 2x - y = 360 - 280 = 80 <----

A person writes all the natural numbers from 100 to 999.?

The number of zero's that he uses is x, the number of fives that he uses is y and the number of eights that he uses is z. What is the value of 2x+2z-3y?

is there any method to find the values of x,y and z

...COUNTING !!

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