So the equation you would have to set up would be: (3m)+(2m-5)=90.
If your wondering where I got the 90 from I got it because the question states it is a right angle.
So now you combine like terms:
3m+2m=5m
Which leaves you:
5m+(-5)=90 or 5m-5=90
Then you do the opposite operation by changing subtraction to addition:
5m-5=90
+5
(Don’t forget your do the same on the other side)
5m-5=90
+5 +5
—————-
And then your left with:
5m=95
Then you divide by 5 on both sides by creating a fraction:
5m=95
—- —-
5 5
And you get your answer:
m=19