First, you know that the sum of all the angles is 540 degrees, so add them all together to find an equation that can be solved for b.
b+(3/2b)+(b-45)+(2b-90)+90=540
Then simplify the equation:
b+(3/2b)+b+2b=540+45+90-90
4b+(3/2b)=585
11/2b=585
11b=585x2
11b=1170
b=1170/11
b=106.36
Using this answer for 'b', you can plug it into the other values for the angles to find the final answers.