First find out the first pair which satisfy the given equation with minimum value of b.
It is (39,3)
The other pairs can be calculated as for the equation, if we increase the value of b by 1 unit, then the value of a must be decreased by 53 unit.
We need values as positive integers only.
So if the value of b is increased by 3 then the value of a is decreased by 5
Next pairs are (34,6),(29,9),(24,12),(19,15)
Next pair is (14,18) but a>b
So the last pair will be (19,15)
So there are 5 pairs which satisfy the given conditions.