Answer:
5 shirts must be sold.
Step-by-step explanation:
First, set up the equation. Each shirt (x) is sold for $16:
For every amount (y) for x: (y)(x) = (16)(y)
The cost is $4, with the setup fee as $60.
(16)(y) = (4)(y) + 60
16y = 4y + 60
Isolate the variable (y). Note the equal sign, what you do to one side, you do to the other. First, subtract 4y from both sides.
16y (-4y) = 4y (-4y) + 60
16y - 4y = 60
12y = 60
Next, isolate the variable (y). Divide 12 from both sides.
(12y)/12 = (60)/12
y = 60/12
y = 5
5 shirts must be sold.
To check, plug in 5 for y in the equation:
16y = 4y + 60
16(5) = 4(5) + 60
Simplify.
16(5) = 4(5) + 60
80 = 4(5) + 60
80 = 20 + 60
80 = 80 (True).
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