Question 1063779
3:4 = x:18  —> 3/4 = x/18 —> x = 18*3/4 = 54/4 = 13.5
4:5 = 18:y  —> 4/5 = 18/y —>  y = 18*5/4 = 90/4 = 22.5

 13.5:18:22.5  satisfies the ratio, and the sum is {{{ highlight(54) }}}

Or we could've just done:   18*3/4 + 18 + 18*5/4 = 54.