Question 911750
x+y=4
x=4-y
r*t+r*t=d

4x+6y=18
4*(4-y)+6y=18
16-4y+6y=18
16+2y=18
2y=2
y=1
x=4-1=3

6*1=6 miles downhill
4*3=12 miles uphill