Answer:
54
Step-by-step explanation:
90 +36 = 126
There is 180 degrees in a triangle.
180 - 126 = 54
Try plugging in 4,6, and -7 into the x's
Answer:

Step-by-step explanation:
we know that
The formula to find the sum is equal to

where
a1 is the first term
an is the last term
n is the number of terms
In this problem we have



substitute the values in the formula
