Solving for acceleration of two blocks with two pulleys

[Che8833]

Homework Statement

If block A has mass M and block b has mass m, find the acceleration of block B assuming that the acceleration of block A equals two times the acceleration of block B.

Relevant Equations

Equation 1: T = Ma1

Equation 2: mg - 2T = ma2

Equation 3: a1 = 2a2

Equation 1: T = Ma1

Equation 2: mg - 2T = ma2

Equation 3: a1 = 2a2

Since a1 = 2a for equation one I get T = 2Ma1

mg - 4Ma1 = ma1

mg = 4Ma1 + ma1

mg = 4a1(M+m)

a1= mg / 4M+m

Not sure if this is correct. Can someone please help to make sure I'm doing this right?
Thanx

 

[quinoa19]

Looks correct, I got same answer,
$a_{\rm B}=\frac{mg}{m+4M}$