Party A and Party B set out from two places 60 kilometers apart. Party A was behind Party B, and the speed of Party A was 80. After 45 hours, Party A caught up with Party B. If Party A started 30 minutes earlier than Party B, how would you like to know How many hours does a catch up with B?

1. Party A and Party B set out from two places 60 kilometers apart. After Party A was behind Party B, the speed of Party A was 80, and the speed of Party B was 45. After a few hours, Party A overtook Party B
60 ÷ (80-45) = 12 / 7 (hours)
2. If a starts 30 minutes earlier than B, ask a how many hours to catch up with B
(60-80 × 0.5) / (80-45) = 20 / 35 = 4 / 7 (hours)

Party A and Party B set out to a certain place by motorcycle from AB, which is 60 kilometers away. Party A is behind Party B, with 80 kilometers per hour and 45 kilometers per hour,
If a starts 30 minutes earlier than B, how long does it take for a to catch up with B
I can't understand this question. There are similar ones on the Internet, but they are all different

Party A and Party B can only start from two different points ab
A walks 80 * 30 / 60 = 40 km 30 minutes in advance, and the distance between a and B is 60-40 = 20 km
Time required: 20 / (80-45) = 4 / 7 (hours)
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AB is 15 kilometers apart. A walks 5 kilometers per hour. B walks 4 kilometers per hour. The two people start from AB and walk backward. After a few hours, they are 60 kilometers apart

AB is 15 kilometers apart. A walks 5 kilometers per hour. B walks 4 kilometers per hour. The two people start from AB and walk backward. After a few hours, they are 60 kilometers apart
Suppose that after X hours, the two people are 60 kilometers apart
Analysis: because starting from AB, AB itself is 15 kilometers away. If a and B vehicles are 60 kilometers away, in fact, they only need to drive 60-15 = 45 kilometers
（4+5）x=45
X = 5 hours

A and B travel from a to B at the same time. It is known that a travels 80 kilometers per hour and B 75 kilometers per hour. A few hours later, B falls 25 kilometers behind a?

25 / (80-75) = 5 hours

Party A and Party B set out from two places 60 kilometers apart. Party A was behind Party B, and the speed of Party A was 80. After 45 hours, Party A caught up with Party B. If Party A started 30 minutes earlier than Party B, how would you like to know How many hours does a catch up with B?