Answer:
40
Step-by-step explanation:
According to the statement we have that both begin at the time.
Gear 1 = 4 turns
Gear 2 = 5 turns
They also do not say that they coincide at turn 20.
If we continue, we can calculate when they coincide again:
1st
20 + 4 = 24
20 + 5 = 25
2nd
24 + 4 = 28
25 + 5 = 30
3rd
28 + 4 = 32
30 + 5 = 35
4th
32 + 4 = 36
35 + 5 = 40
5th
36 + 4 = 40
They therefore coincide again at turn 40.
