Your minimum of steps is 300, and you have already have climbed 175 steps.
You would base your equation as 300 ≤ n + 175.
But, you need to fix the equation on one unit. Let's go with the stairs route.
If he goes up 10 more flights, you can multiply the amount of steps per flight (12) by the amount of flights (10).
10 × 12 = 120
So, you need to figure out if 300 ≤ 120 + 170 is a true statement. Solving it would be adding 120 to 170.
120 + 170 = 290
Well, 300 is not ≤ 290, so the answer would be no, he wouldn't reach his goal.