Question 225857
f a certain number is added to the numerator and denominator of 7/15, the result is 1/3, find the number?
:
let x = "the number"
:
{{{(x+7)/(x+15)}}} = {{{1/3}}}
cross multiply
3(x + 7) = 1(x + 15)
3x + 21 = x + 15
3x - x = 15 - 21
2x = -6
x = -3 is the certain number
:
:
Check
{{{(-3+7)/(-3+15)}}} = {{{1/3}}}
{{{(4)/(12)}}} = {{{1/3}}}