Hello,
To find this solution, you have to write an inequality. We want the new plan to be less than the old plan of $175.
So our inequality would be:
94 + 4.5x < 175
Solving it gives:
4.5x < 81
x < 18
So the number of devices must be less than 18. Draw an open circle at 18 with a ray going to the left to show those numbers.
Good luck,
MrEQ