A grade is A for 90 or more, B for 75 or more, C for 50 or more and D for less than 50.

Plan. Check from the highest grade down, with elif.

• $82$: the first condition 82 >= 90 is false. The second, 82 >= 75, is true. Grade B.
• $90$: 90 >= 90 is true, because >= includes 90. Grade A.
• $49$: all three conditions are false, so else gives grade D.

Answer: B, A and D.