To find Johan's rate of speed (r), you can rearrange the formula \( d = rt \) to solve for \( r \):
\[ r = \frac{d}{t} \]
In this case, Johan travels \( d = 35 \) miles in \( t = 1.75 \) hours. Plugging in these values:
\[ r = \frac{35 \text{ miles}}{1.75 \text{ hours}} = 20 \text{ miles per hour} \]
So, Johan's rate of speed is 20 miles per hour.