First, find the mean. You'll need it to compute the variance.

The variance of the sample is then computed with the formula

The standard deviation is the square root of the variance, so
Answer:
10°
Step-by-step explanation:
According remote interior angles, 4k + 5 + 6k + 10 = 115.
10k + 15 = 115
10k = 100
k = 10
Hope this helps :)
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I cant type it out so here is a photo