Answer:
45 + 3m = 75
Explanation:
**You haven't provided the options for the solution in your question**
However, from the information provided, the equation representing the situation is:
45 + 3m = 75
To solve 45 + 3m = 75:
Subtract 45 from both sides: 3m = 30
Divide both sides by 3: m = 10
Therefore he solved 10 math problems.