A machine makes \(9\)-inch, \(4\)-inch, and \(7\)-inch parts. During …

Question

Prompt

A machine makes

9

-inch,

4

-inch, and

7

-inch parts. During a certain day, the number of

9

-inch parts that the machine makes is

3

times the number

n

4

-inch parts, and the number of

7

-inch parts is

12

. During this day, the machine makes

100

parts total. Which equation represents this situation?

9 n + 4 n + 7 n = 100

4 n + 12 = 100

9 (3 n) + 4 n + 7 (12) = 100

3 n + 12 = 100