D. Find P(X ≤ 45)= P(45) + P(42) + P(40) + P(37) + P(35)

= 3/10 + 1/5 + 1/10 + 1/5 + 1/10

= 3/10 + 2/10 + 1/10 + 2/10 + 1/10

= 9/10 or 0.90

Other solution:

Find P(X ≤ 45)= 1 -P(50)

= 1 – 1/10

= 9/10