It is 20 because if u divide 78 by 3.75 ( 3 3/4 ) than equals 20.8
Answer:

Step-by-step explanation:
Step 1:
Convert the mixed numbers to the improper fractions:

Step 2:
We multiply the numbers remembering about simplifying:

The surface area of the cone will be : 169.65 so it would be answer A as 54 x pi = 169.646003