So what you want to do is use PEMDAS.
P stands for parentheses and so you solve everything in parentheses first:
(-7+31)-(2-61) = (24)-(-59)
And next we multiply, as there is no exponents. Since there are two negatives in front of the 59, that makes the 59 become positive.
So now we have: 24+59
Finally we add them together as the A in PEMDAS.
24+59= 83
So your answer is 83, I hope this helps!