So basically it seems that you can just give any value to a and b as long as the statement given is true. 4 & 5 can work for the part of the problem.
a = 4; b = 5
Plugged in:
4 + 1 = 5 (b > a; 5 > 4)
Therefore the statement is true. This is proof that it is.
Part B is asking when can the statement be false and what numbers prove that if possible.
It is possible for there to be values for a and b in which the relationship given turns false. For example, a = 4 and b = 3 makes the statement false since 4 + 1 doesn't equal 3 and 3 is not greater than its a-value of 4.
Hope this helps!