what is 6 over 6b + 4 = 2 over b - 4

6 / (6b + 4)  =  2 / (b - 4)

Cross multiply:  6(b - 4)  =  2(6b + 4)

Distribute:        6b - 24  =  12b + 8

Subtract 6b:         - 24  =  6b + 8

Subtract 8:           - 32  =  6b

Divide by 6:          -16/3  =  b