Answer:
170
Explanation:
Given that: x represents total number of keyboards ordered
y represents number of non-defective keyboards
And;
y = 0.9x -
.......................... 1
If the college ordered 200 keyboards, then x = 200. So that substituting the value of x in equation 1, we have;
y = (0.9 x 200) -

= 180 -

= 180 - 10
y = 170
The college received 170 non-defective keyboards.