Mike observed that 75% of the students of a school liked skating. if 35 students of the school didn't like skating, the number of students who liked skating was

Cross multiply.

75 / x = 25 / 35

25x = 35 (75)

25x = 2625

/25 / 25

x = 105

Therefore 105 students liked skating.

Proof:

105 + 35 = 140.

140 * 0.75 = 105

140 * 0.25 = 35

140 (total) split into quarters.

35 + 35 + 35 + 35 = 140

35 + 35 + 35 = 105 (3 quarters liked)

35 = 35 (1 quarter disliked)