a/a+3 - a-4/a
subtract and simplify
a / (a + 3) - (a - 4) / a.
(a^2 -(a - 4)(a + 3)) / a(a + 3) =
(a^2-(a^2 - 3a - 4a - 12)) / a(a + 3)=
(a^2 - (a^2 - a - 12)) / a(a + 3) =
(a^2 - a^2 + a + 12) / a(a + 3) =
(a + 12) / a(a + 3).
subtract and simplify
(a^2 -(a - 4)(a + 3)) / a(a + 3) =
(a^2-(a^2 - 3a - 4a - 12)) / a(a + 3)=
(a^2 - (a^2 - a - 12)) / a(a + 3) =
(a^2 - a^2 + a + 12) / a(a + 3) =
(a + 12) / a(a + 3).