D/60 + D/50 = 2D/55 - 1/2
find common denominator ( 3300)
3300/60 = 55
3300/50 = 66
3300/55=60
so then you get 55D +66D= 60(2D)-1650
121D=120D-1650
D=1650 miles
check
1650/60 =27.5, 1650/50 = 33, 27.5 + 33 = 60.5 hours total
1650/55 = 30, 30 x 2 = 60
60.5-60 = 0.5 longer
so distance = 1650 miles
Subtract a number from the next number.
39 - 45 = -6
Answer: B. -6
