The sum of two numbers is 77 and their ratio is 6 : 5. What is their difference?

4 6 7 5

7

A : B = 6 : 5 A + B = 77 ⇒ (A + B) units = 77, ⇒ 11 units = 77, ⇒ 1 units = 7, ⇒ A - B = 6 - 5 = 1 x 7 = 7.