Answer: 1.2miles
Step-by-step explanation:
Divide 15 by 50 to get how far she rides in 1 minute that multiply that by 60 to get how far she rides in 1 hour.
Given:
The number of teeth = t = 25
The gear is driven by a 10-tooth driver gear (T) at 250 RPM
Let the speed = s
So, using the ratio and proportion

Solve for s:

So, the fear will be driven by 625 RP

I hope this this is what you need ..
I think it is y=-.25
7*3 - 4y = 20
21 - 4y = 20
subtract 21 from each side
- 4y = - 1
divide each side by - 4
y= -.25