Answer:
2x - 7
Step-by-step explanation:
Twice a number x means x times 2, which can be written as 2x
Minus 17 from 2x
.......,,,,,....,..,....,.
For a question like this, all you have to do is remember that a percentage is simply a fraction expressed as a decimal. So, all we have to do is:

, and then multiply our decimal answer by 100 to get the percentage:

= 0.34
0.34 x 100 = 34
Therefore 34% of the students walk to school.
I hope this helped and remember to please try and understand the maths that got the answer, not just writing the answer down :))