x = Lilys weight
x + 34 = Arthurs weight
4x - 180 = combined weight
x + x + 34 = 4x = 180
2x + 34 = 4x - 180
-2x -2x
_________________
34 = 2x -180
+180 + 180
_______________
214 = 2x
107 = x which is Lily's weight
141 = x + 34 which is Arthur's weight
The total weight is 248
which is the answer that you get when you do 4(107) = 180 or
428 -180 = 248
