Triangle angles add up to a total of 180 degrees.
X will substitute for the second angle.
(X - 10) will substitute for the first angle, which is 10 less than the second angle (x).
The third angle is a right angle which is 90 degrees.
The equation therefore, the summation of the angles:
90 + x + (x - 10) = 180
Join like terms:
80 + 2x = 180
Solve for x:
2x = 100
x = 50
This means that:
The second angle is 50.
The first angle is 50 - 10 which is 40.
We can double check by adding the angles 50, 40, and 90 together to get 180.
