Answer:
This year:
dads: 36 years
Alex: 6 years
Step-by-step explanation:
a = d/6
a+4 = (d+4)/4
a = Alex´s actual age
d = actual age of the dad
d/6 + 4 = (d+4)/4
4{(d/6) + 4} = d+4
4*d/6 + 4*4 = d+4
4d/6 + 16 = d + 4
4d/6 = d + 4 - 16
4d = (d-12)*6
4d = 6*d +6*-12
4d = 6d - 72
4d - 6d = -72
-2d = -72
d = -72/-2
d = 36
a = d/6
a = 36/6
a = 6
probe:
a+4 = (d+4)/4
6 + 4 = (36+4)/4
10 = 40/4
