Step-by-step explanation:
upper left angle and lower right are the same in a parallelogram (the other two angles match as well, but aren't useful)
so we can write this equation:
3x -15 = 2x +24
1x -15 = 24
x = 39
always do the same thing on both sides of an equation (here: subtract 2x, then add 15)
now you might give it a try yourself with the next problem that got two same things in it.
always grow stronger :)
