Question 839792
set = the first number
y = second number
x/y = 8/9
y-x = 10 
solve for y in the second equation
add x to each side
y = x + 10
substitute x + 10 for y in x/y = 8/9
{{{x/(x + 10) = 8/9}}}
do cross products
{{{9x = 8(x+10)}}}
{{{9x = 8x + 80}}}
add -8x to each side
x = 80
since x/y =8/9 with x = 80, y = 90