3x18 = 24? 3x18 = 54.
I'd also add that you added your 24 and 36 to get 60. Then you added 100, not 90, to that to get 160. In fact, it's 90+60 which is 150.
Keep practicing, you'll get there! You were doing great until you made those two mistakes. You've got the general idea of it.