Question 200387
Let cheese pizza be C and mushroom pizza be M
Given {{{3C + 4M = 12.50}}}
and
{{{3C + 2M = 8.50}}}
Using elimination 
{{{3C + 4M = 12.50}}}
{{{3C + 2M = 8.50}}}
------------------------   subtract the second equation from the first one to get
{{{2M = 4.00}}}
Solve for M 
{{{M = 2.00}}}  mushroom slice costs $2 each
Using that info, substitute for M in either equation to find C
{{{3C + 2M = 8.50}}}
{{{3C + 2*2 = 8.50}}}
{{{3C + 4 = 8.50}}}
{{{3C = 4.50}}}
{{{C = 1.50}}}