The average of four numbers is 98. If three of the numbers are 86,87, and 91 what is the fourth number?

To find the average, you have to add all the numbers up and then divide by the amount of numbers you added together.

Equation: (86+87+91+x) / 4=98

Solve for x:

86+87+91+x=98*4

264+x=392

x=392-264

x=128

The fourth number is 128