Answer:
A = (Z-CD - EFG)/B
Step-by-step explanation:
AB + CD + EFG = Z.
Subtract CD and EFG from each side
AB + CD + EFG-CD -EFG = Z-CD - EFG
AB = Z-CD - EFG
Divide each side by B
AB /B = (Z-CD - EFG)/B
A = (Z-CD - EFG)/B
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