| Age at Present | Age 20 years from the present | |
| Father | F | F+20 |
| Son(John) | J | J+20 |
| Relationship | \(J = 0.30 F\) | J+20 = 0.58 (F+20) |
\(J+20 = 0.58F + 11.6\)
\(0.30F+20 = 0.58F + 11.6\)
\(F = 30\)
\(J = 0.30(30) = 9\)
Thus, the father's age at present is 30 years old and the son (John) is 9 years old.