Answer:
x = 5
Step-by-step explanation:
a) The third interior angle of this triangle is 180 - 20 x.
The three interior angles must sum up to 180 degrees.
Therefore, 60 + 7x + 5 + 180 - 20x = 180, or
65 + 180 - 13x = 180, or
65 - 13x = 0
Finally, 13x = 65, and so x = 5
Use the protractor. Put the purple dot on the vertice and the make sure the line is lined up with the bottom and your answer should be lined up.
Standard error (SE)

Or

Therefore, SE of the mean = (8)/(2) =4
Sometimes it helps to draw it out...
(17)
C_______M_________Q
|___________________|
21
therefore, CM + MQ = CQ
17 + MQ = 21
MQ = 21 - 17
MQ = 4 <===