Equation

4 + 6(12k - 4) = .4(4k - 16) - 3   
4 + 72k - 24 = 1.6k - 6.4 - 3
72k - 20 = 1.6k - 9.4
72k - 1.6k = 20 - 9.4
70.4k = 10.6
k = 10.6/70.4

return