Given:
Line m is parallel to line n.
The measure of ∠1 is (4x + 15)°
The measure of ∠2 is (9x + 35)°
We need to determine the measure of ∠1
Value of x:
From the figure, it is obvious that ∠1 and ∠2 are linear pairs.
Thus, we have;

Substituting the measures of ∠1 and ∠2, we get;




Thus, the value of x is 10.
Measure of ∠1:
The measure of ∠1 can be determined by substituting x = 10 in the measure of ∠1
Thus, we have;



Thus, the measure of ∠1 is 55°