ok so
fater=60
son is 1/2
60 times 1/2=30
they aer 30 years apart
how long ago was father age 4 times son age
father's age x year ago=60-x
son's age x years ago=30-x
60-x=4(30-x)
distribute
60-x=120-4x
add 4x to both sides
60+3x=120
minus 60 from both sides
3x=60
divide both sides by 3
x=20
20 years ago
30-20=10
the boy was 10 years old
