First what you would do is replace the v in 20v with 19 like so 20(19) and that would give you 380. Next you would replace the d in 12d with 12(20) and that would give you 240. Then replace the v in -6v with -6(19) and that would give you -114. Add them together and you get 506. The reason why -6x19= -114 is that a negitive times a positive equals a negitive. Or......
