Help please with physics momentum problem

solve for m_boy:
0 = (8kg)(2.9m/s) + (m_boy + 1.9kg)(−0.57m/s)

Come on man, seriously? I understand that the other problems have a scientific perspective you must add to solve them, but this is a simple algebra problem. You need serious academic help. I'll help you anyways.

0=22.12 + m_boy(-.57)

-22.12=m_boy(-.57)

m_boy=38.8 kg

0 = (8kg)(2.9m/s) + (m_boy + 1.9kg)(−0.57m/s)
0 = 8x2.9 + (m + 1.9) x-0.57
0 = 23.2 -0.57m - 1.9x0.57
0 = 23.2 - 0.57m - 1.083
0 = 22.117 - 0.57m
0.57m = 22.117
m = 22.117/0.57 = 38.80kg

38.8 kg