﹙75-60﹚×χ=60×0.5

15χ=30

χ=30÷ 15

χ=2

A: The bus caught up with the bus two hours later.

2. Solution: It is assumed that all goods can be delivered after χ days.

﹙ 1.25-0.5﹚χ=7.5

0.75χ=7.5

χ= 10

A: After 10, everything can be shipped away.

3. Solution: Let the ship run at a speed of χ kilometers per hour.

﹙38-χ﹚×4=24

38-χ=6

χ=32

A: The ship travels 32 kilometers per hour.

4. Solution: Let group B work for χ hours, and the processing times of the two groups are equal.

﹙50-40﹚×χ=30

10χ=30

χ=3

A: After working for 3 hours in group B, the processing capacity of the two groups is equal.

5. Solution: Set car B to drive χ kilometers per hour.

﹙45+χ﹚×5-45=480

﹙45+χ﹚×5=525

45+χ= 105

χ=60

A: Car B runs at 60 kilometers per hour.