Question 1052392
Let Aminu's age be x:
x-4 = 1/2(x+8) multiply both sides times 2
2x-8 = x+8 Add 8 on both sides and subtract x on both sides
x = 16
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Check:
x-4 = 1/2(x+8)
16-4 = 1/2(16+8)
16-4 = 8+4 
12 = 12 Correct
:
John