If you mean:
4/(2y) + 49/(7y)
then:
4/(2y) * (7/7) + 49/(7y) * (2/2)
28/(14y) + 98/(14y)
(28 + 98) / (14y)
126 / (14y)
9 / y
If you mean:
(4/2)y + (49/7)y
Then:
y ( 4/2 + 49/7 )
y ( 4/2 * 7/7 + 49/7 * 2/2 )
y ( 28/14 + 98/14 )
y ( 126/14 )
y ( 9 )
9y