In an exam, Amy, Bob, Carl and David scored an average of 75% each. Amy scored 60%. The combined scores of Bob and Carl were 40% more than the score of David. What score did David get?

%

The total score of all four people: 75% × 4 = 300%

The total of score of Bob, Carl and David: 300% – 60% = 240%

Think of the 240% as being the sum of two numbers: Bob and Carl’s combined score and David’s score. Since Bob and Carl’s combined score is 40% more than David’s score, subtract 40% from 240% and this will give you double what David scored.

240% – 40% = 200%

200% ÷ 2 = 100%

David scored 100%.