If the cost price is 60% of the selling price, then what is the profit percentage? 

Correct option is C

Given:

Cost Price (C.P.) = 60% of Selling Price (S.P.)

Formula Used:
Profit Percentage =$$\dfrac{\text{Profit}}{\text{Cost Price}} \times 100$$​​
Profit = Selling Price - Cost Price

Solution:
Let the Selling Price be S.P.
Cost Price = 60% of Selling Price $$= \dfrac{60}{100} \times S.P. = 0.6 \times S.P.$$​​

Profit = Selling Price - Cost Price
Profit = S.P. $$- 0.6 \times S.P. = 0.4 \times S.P.$$​​

Profit Percentage =​$$\dfrac{0.4 \times S.P.}{0.6 \times S.P.} \times 100 = \dfrac{0.4}{0.6} \times 100 = 66\frac 23\%$$​