The value of x is C) 7
First, we know that this is a right angle and it measures 90 degrees. We have to angle measurements that are given so we need to find out what x is.
So, we will subtract 55 from 90. 90-55= 35.
Now, we will have to set 5x equal to 35 and divide in both sides of the equation.
5x=35. 5 divided by 5 is 1. And 35 divided by 5 is 7 so that leaves us with x=7.
Hope this helps! :)