Answer:
Blueberry costs 9 dollars
Pumpkin costs 7 dollars
Step-by-step explanation:
Let "b" represent the price of a blueberry pie
Let "p" represent the price of a pumpkin pie
Step 1: Set equation
5b + 12p = 143 ----- 1
10b + 8p = 142 ----- 2
Step 2: Isolate 1 for "b"
5b = 143 - 12p
[tex]b = \frac{143}{5}-\frac{12}{5}p[/tex] ------- 3
Step 3: Substitute 3 into 2
[tex]10(\frac{143}{5}-\frac{12}{5} p )+8p=142\\286 - 24p + 8p = 142\\-24p + 8p = 142 - 286\\-16p = -144\\p = -\frac{144}{-16}\\ p = 9[/tex]
Step 4: Subsitute p = 9 into 1 for b
[tex]5p + 12(9) = 143\\5p + 108 = 143\\5p = 143 - 108\\5p = 35\\\frac{5p}{5}=\frac{35}{5}\\p = 7[/tex]
Therefore a pumpkin pie costs 7 dollars while a blueberry pie costs 9 dollars