Solution: Suppose the father jumps once a minute and the son jumps () times a minute ... 1 minute.

Judging from the meaning of the question: 2 points.

Simplify:

............................. 1 min.

It is proved that it is the solution of the equation ....................................................... 1 min.

∴

A: The father jumps 120 times a minute and the son jumps 140 times a minute. ...... 1 (***6)