Answer: Shirts are $9 each and hats are $8 each
Step-by-step explanation:
Let S be the price of a Shirt, and H the price of a Hat.
First Week: 4S + 9H = $108
Today: 17S + 21H = $321
We have 2 equations and 2 unknowns (S and H). Rearrange one of the equations to isolate one of the unknowns. I'll rearrange the first for S:
4S + 9H = $108
4S = $108 - 9H
S = ($108 - 9H)/4
S = 27 - 2.25H
Now use this value of S in the second equation:
17S + 21H = $321
17(($27 - 2.25H) + 21H = $321
Solve for H:
459 -38.25H + 21H = $321
-17.25H = - 138
H = $8
Each hat was $8.
Use this value in the first equation to find S:
4S + 9H = $108
4S + 9*($8) = $108
4S + $72 = $108
S = $9
Each shirt was $9.
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Check to see if the numbers give the correct results:
4*($9) + 9*($8) = $108
17*($9) + 21*($8) = $321
Both yield the correct amounts. Shirts are $9 each and hats are $8 each.
