Answer:
3.5 hours was taken by the journey in the hills.
Step-by-step explanation:
Total of 273 miles.
In the plains, 175 miles.
The rest(x), on the hills.
So
175 + x = 273
x = 273 - 175
x = 98
98 miles in the hills, at the speed of 28 miles/hr.
To find the time, we can solve a rule of three.
1 hr - 28 miles
x hrs - 98 miles
3.5 hours was taken by the journey in the hills.