
Multiply 20 by 5 to get 100 so multiply the 3 by 5 also to get 15% of the days.
Since this is a right triangle, we could use the pythagorean theorem: a²+b²=c² where this problem already gave us a=10 and b=√60, and we want to solve for c.
10²+(√60)²=c² ← 10² is 100, and the square cancels out the square root on the 60
100 + 60 = c²
160 = c² ← To isolate c, we take the square root of both sides
√160 = c ← √160 is the same as 4√10
Answer: 4√10
The correct answer is 18 . if you follow pemdas it really helps.