There are four numbers. If we leave out any one number,the average of the remaining three numbers will be 45,60,65 or 70.What is the average of all four numbers?

Question

It is a progress check.

Answer 1

(n₁ + n₂ + n₃₎/3 = 45

(n₂ + n₃ + n₄)/3 = 60

(n₁ + n₂ + n₄)/3 = 65

(n₁ + n₃ + n₄)/3 = 70

Now you have to setup 4 equations to solve for the 4 unknowns.