Question 411054
Let buy x T-shirts, and y-shorts. If you have to buy a total of 8 T-shirts and shorts, then {{{x+y=8}}}
T-shirts cost $10 each, so for x T-shirts you'll spend {{{10x}}}$, shorts cost $15 each, so you'll pay {{{15y}}}$ for y shorts/ Then you'll spend {{{10x+15y}}}
System of equations
{{{system(10x+15y=90,x+y=8)}}}
{{{system(10x+15y=90,y=8-x)}}}
{{{system(10x+15(8-x)=90,y=8-x)}}}
{{{system(10x+120-15x=90,y=8-x)}}}
{{{system(5x=30,y=8-x)}}}
{{{system(x=6,y=8-x)}}}
{{{system(x=6,y=8-6)}}}
{{{system(x=6,y=2)}}}
So, you have to buy 8 T-shirts, 2 shorts.