If f(a)=4a−1f(a) = 4a - 1f(a)=4a−1 and g(a)=a+2g(a) = a + 2g(a)=a+2, what is the expression for the composition (f∘g)(a)(f \circ g)(a)(f∘g)(a)?
4a+74a + 74a+7
4a+14a + 14a+1
4a+64a + 64a+6
5a+15a + 15a+1