So, there are 3.785 liters to a US gallon, and there are 1.609 km to 1 mile
so, to convert 30 m/g to l/km
simplify away, cancel units as needed
Let the walker’s speed be W, then the biker’s is W+1.5W=2.5W. Difference in speed is 1.5W. Distance=speed times time, so 12.5=1.5W×1.5=2.25W, and W=12.5/2.25=1250/225=50/9=5.56 mph. The biker’s speed is 2.5W=125/9=13.89 mph to 2 Dec places.
(Note: “1.5 times faster than a walker’s speed” could not reasonably mean the biker’s speed=1.5W because this would give W=16.67 mph, which is very fast for a runner, let alone a walker (!), and a biker’s speed of 25mph.)
I got 1/12th left
I changed all of the fractions to twelfths
4/12
6/12
9/12
16/12
James and Katya ate 10/12 of a sandwich
Ramon ate the last 2/12 and 7/12 of the next sandwich
Sianna ate the other 5/12 and 11/12 of the 3rd sandwich
So that means 1/12 is left
I hope that helps and you get it right