Question 1064296
f = 4s

f+16 = 2(s+16)
f+16 = 2s+32
4s+16 = 2s+32
2s = 16
s = 8 the son is 8 
and the father:
f = 4s = 4(8) = 32 the father is 32.
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In 16 years:
father: 32+16 = 48
son . : 8+16 = 24 and twice as old as the son: 24*2 = 48 Correct!