Marianne is completing a 4-mile route for charity. Every io mile is marked along the
route. For each mile, she runs 7 mile and
walks mile. How many miles does
Marianne run?

For 1 miles distance: 7/10 of a mile she runs and 3/10 she walks.

For 4 miles distance (4 times the previous distance) she will run:

4*(7/10) = 18/20 = 2.8 miles

and walk:

4*(3/10) = 12/10 = 1.2 miles.