We assume , A, B, and C are angles of a triangle.
The sum of angles of a triangle is equal to 180º; therefore:
A+B+C=180º
B is 45% of angle A; then B=0.45A
C is 35% of anble A; Then C=0.35A
We can suggest this equation;
A+0.45A+0.35A=180
1.8A=180
A=180/1.8
A=100
Answer: The measurement of angle A is 100º.