To find Johan's rate of speed in miles per hour, we can use the distance formula \( d = r \times t \), where:
- \( d \) is the distance traveled,
- \( r \) is the rate of speed, and
- \( t \) is the length of time traveled.
In Johan's case:
- \( d = 35 \) miles,
- \( t = 1.75 \) hours.
We need to solve for \( r \), so we can rearrange the formula to:
\[ r = \frac{d}{t} \]
Now, we can plug in the values for distance and time:
\[ r = \frac{35 \text{ miles}}{1.75 \text{ hours}} \]
Next, we perform the division:
\[ r = 20 \text{ miles per hour} \]
Thus, Johan travels at a rate of 20 miles per hour.
In conclusion, the correct response is: Johan travels at a rate of 20 miles per hour.