Hi there!
The sum of the angles in a triangle always adds up to 180°.
We can also make a mathematical expression to find the sum of the angles. Let's add the angles.
First remove the parenthesis.
Now collect the common terms.
We've now found our expression that expresses the sum of the angles. Since the sum of these angles also equals 180°, we can set up an equation.
Start the solving by subtracting 42 from both sides.
And finally divide by 2.
The value of x in the triangle is therefore 69°.
Now we can easily find the measure of angle H, by plugging in 69° in the expression that indicates the measurement of H.
Hence, the answer is C. 68°
~ Hope this helps you!