The measure of arc LM is 116
The measure angle MBL is 58
The measure of angle MNL is 64
They are also perpendicular to the top line of the roof
You can put the -4 and -9 together and put it at the end to make the new sequence 4-13 which would leave you with -9
we are given

we can see that
4a is in multiple in numerator
so, we can factor it out

now, we can cancel 4a
and we get
.............Answer