Answer:
Let's imagine that x is the number of 3 pound weights that the gym instructer has.
Since we know that there are 10 more 5 pound weights, which tells us that the number of 5 pound weight is x + 10, and the total amount is 60 hand weights, we have:
x + x + 10 = 60
2x = 60 - 10
2x = 50
x = 50/2 = 25
So there are 25 3 pound weights at the gym.
From the number we have just found, we also know that the number of the 5 pound weights should be:
60 - 25 = 35 (hand weights)
