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
In 1 hour, a machine could make:

parts
In 28.8 hours, that machine make

parts
Answer:

Step-by-step explanation:

First, simplify
:


Hope this helps!