SOLUTION: Hello there, I have an equation that I have worked the answer out for in my head but I cannot work out how to write the formula. Please could someone help me with the formula, Than

Algebra ->  Systems-of-equations -> SOLUTION: Hello there, I have an equation that I have worked the answer out for in my head but I cannot work out how to write the formula. Please could someone help me with the formula, Than      Log On


   



Question 602717: Hello there, I have an equation that I have worked the answer out for in my head but I cannot work out how to write the formula. Please could someone help me with the formula, Thank you. The equation is : Greg bats in 7 cricket matches, in the 8th match he makes 9 runs and his average decreases by one. How many runs has he made in all?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Greg bats in 7 cricket matches, in the 8th match he makes 9 runs and his average decreases by one.
How many runs has he made in all?
:
Let x = number of runs in all
then
(x-9) = number of runs in the first 7 matches
:
7 match average - 1 = 8 match average
%28x-9%29%2F7 - 1 = x%2F8
multiply by 56 to clear the denominators
8(x-9) - 56 = 7x
8x - 72 - 56 = 7x
8x - 128 = 7x
8x - 7x = 128
x = 128 runs in all