Answer:
39 degrees
Step-by-step explanation:
The wall and the ground form a right angle which means that they form an angle of 90 degrees. Then, the sum of the angle the beam makes with the wall and 51 degrees is equal to 90. So
x + 51 = 90
Now, we can solve for x, subtracting 51 from both sides
x + 51 - 51 = 90 - 51
x = 39
Therefore, the measure of the angle the beam makes with the wall is 39 degrees.