Answer:
21
Step-by-step explanation:
Green bat: x
Purple bat: y
Pumpkin: z
Given:
2x + y = 40
y - z = 7 ===> y = 7 + z
z + x = 19 ===> z = 19 - x
Substitution to find green bat x:
2x + y = 40
2x + (7 + z) = 40
2x + 7 + z = 40
2x + 7 + (19 - x) = 40
2x + 7 + 19 - x = 40
x + 26 = 40
green bat: x = 14
Substitution to find pumpkin z:
z + x = 19
z + (14) = 19
z + 14 = 19
pumpkin: z = 5
Substitution to find purple bat y:
y - z = 7
y - (5) = 7
y - 5 = 7
purple bat: y = 12
Solve for x - z + y:
14 - 5 + 12 = 21
