846
Step-by-step explanation:
Answer:
11 in
Step-by-step explanation:
The area of a square is given by
A = s^2 where s is the side length
121 = s^2
Taking the square root of each side
sqrt(121) = sqrt(s^2)
11= s

Hope you could get an idea from here.
Doubt clarification - use comment section.
I am assuming that the cost of an oil change already includes the mark-up.
So, 18 is 175%. 18 ÷ 1.75 = 10.29 is the original cost.
10.29 * 3/4 = 30.87/4 = 7.71 mark-up
10.29 + 7.71 = 18
Or if 18 is the basis of the mark-up, then,
18 * 3/4 = 54/4 = 13.50 mark-up
18 + 13.50 = 31.50 new cost of an oil change