First you have to simplify the equations
7w+7= (4w) + (-4+23) 7w+7= 4w+19
Than you have to subtract the 4w (both equation)
7w+7-4w =4w = 4w + 19 - 4w = 3w+7= 19
And than you have to subtract the sevens
3w+7-7=19-7=3w=12
than divide by 3
3w/3 equals 12/3w=4
