We can complicate things a bit more. The object the child is holding is tilted one to the right and one to the left, so we can conclude that one is positive and the other is negative, haha.
10 + (x + 4 - 4) * 4 = y
10 + (x + 0) * 4 = y
10 + (x) * 4 = y
10 + 4x = y
y = 4x + 10
What do you think, @coyotelation?
I'm out here digging back into middle school math ... my brain was like, "Wait, what?" as it was ... so I didn't even think about positive and negative...