I’m having a lot of trouble with this problem. Please help!

First, you need to find what b equals. The equation inorder to find b is:
144=b+b+(2b+3)+(2b+3)
144=6b+6
138=6b
23=b
You would then plug is in to the height equation: 2b+3
2(23)+3= 46+3 =49
Basically, for this equation we plugged all the sides equal to the perimeter so we can find b and then we plugged it in to the equation for height.