Question 816587
{{{x}}} =  cost per gallon of paint and {{{y}}} = cost per brush
Day 1 : {{{8x + 3y = 152.50}}}
Day 2 : {{{6x + 2y = 113.00}}}



We are going to solve day 2 for y so we can plug y into day 1.
{{{6x + 2y = 113.00}}}
{{{2y = -6x + 113.00}}}
{{{y = -3x + 56.50}}}
Now since we know what y equals, we can use the substitution method and plug y into the day 1 equation. 



{{{8x + 3(-3x + 56.50) = 152.50}}}
{{{8x - 9x + 169.50 = 152.50}}}
{{{-x + 169.50 = 152.50}}}
{{{-x = -17}}}
{{{x = 17}}}

the cost of a gallon of paint is $17.  plug 17 in for x in the day 1 equation to find y.



{{{8(17) + 3y = 152.50}}}
{{{136 + 3y = 152.50}}}
{{{3y = 16.50}}}
{{{y = 5.50}}}

The cost of a single brush is $5.50.