Answer:
85%
Explanation:
Justin has ridden 34 miles out of 40 miles. This can be expressed as a fraction, 34/40.
If you carry out the division 34 รท 40, you get 0.85. This is the proportion of the course that Justin has ridden, and is always less than one. To convert this to a percentage, you multiply it by 100:
0.85 * 100 = 85%