Let a and b represent the fractions.
.. a +b = 3(b -a)
.. 6a -b = 3/2
Rewriting the first equation, we have
.. 4a -2b = 0
or
.. 2a -b = 0
Subtracting this from the second equation gives
.. 4a = 3/2
.. a = 3/8
.. b = 2a = 3/4
The two fractions are 3/8 and 3/4.