I assume this means that M is less than the variable 4, which is 82 degrees. So now you want to find what M is if it’s less than the variable 5, we I assume would be greater than 4 but less than 5, meaning greater than 82 degrees, but not by much. I’d say the answer is 90 degrees, as it’s greater than the value 82 but is reasonable as the variable deviates by 1.