Straight line = 180
180 = 4x+30 + 8x+90 solve for 'x' then MON = 8x+90 o
So we know that angle LON is a straight angle. This means that angle LON is 180 degrees.
We are given that angle LOM is equal to 4x+30 degrees. So, we know that the sum of LOM+MON= 180 degrees:
Now, we can substitute this in the equation for MON!
8x+90= 8(5)+90=40+90=130 degrees