Answer:
Just solve the equations simultaneously
Explanation:
x + y = 152 -----------(1)
8.5x+ 12y = 1656 ----------(2)
From equation (1)
y = 152 - x ----------(3)
From equation (3) and equation (2)
8.5x + 12 (152-x) = 1656
8.5x -12x + 1824 = 1656
-3.5x = -168
x = 48
From equation (3)
y = 152 - 48
y = 104
So, the number of hats sold is 48.
Also, if you're using a graphing calculator to solve this question, all you have to do is draw the graphs of x + y = 152 and 8.5x + 12y = 1656.
The values of x and y are given by the intersecting point of the two graphs.