The present ages of three friends are in proportions 3 ∶ 5 ∶ 7. Four years ago, the sum of their ages was 48. What are the present ages of all three friends (in years) ?
1
12 years, 20 years and 28 years
2
15 years, 21 years and 28 years
3
12 years, 25 years and 30 years
4
16 years, 20 years and 28 years