I need help with this advance mean problem?

Question

The problem is:

There is four number the average of the four numbers are 90. When a number was taken away the average of the remaining three numbers was 85. For this data what are the four numbers

Answer 1

Your given equations are as follows:

(A+B+C+D)/4 = 90

(A+B+C)/3 = 85

There is no explicit solution to all four numbers (2 equations, 4 unknowns), but you can solve for the number taken away.

Two solutions are as follows:

85, 85, 85, 105, with 105 being the removed number

84, 85, 86, 105, with 105 being the removed number

Answer 2

75 85 95 and 105 is a combo I can think of... take away 105 to get average of 85.

Maybe I didn't understand the problem correctly...