Answer:
3ab
-------------------
(b+a)
Step-by-step explanation:
3/a - 3/b
-------------------
1/a^2 - 1/b^2
Multiply the top and bottom by a^2 b^2/ a^2/b^2 to clear the fractions
(3/a - 3/b) a^2 b^2
-------------------
(1/a^2 - 1/b^2) a^2b^2
3ab^2 - 3 a^2 b
-------------------
b^2 - a^2
Factor out 3ab on the top
3ab( b-a)
-------------------
b^2 - a^2
The bottom is the difference of squares
3ab( b-a)
-------------------
(b-a) (b+a)
Cancel like terms from the top and bottom
3ab
-------------------
(b+a)
