A comes after B.
28
kilometre (km)
, two people at the same time in the same direction, a line every hour.
16
kilometre (km)
, b per hour.
nine
kilometre (km)
How many hours does it take for A to catch up with B?
Analysis: A has more rows per hour than B (
16-9
) kilometers, that is, A can catch up with B (
16-9
) kilometers, this is the speed difference.
It is known that A comes after B.
28
kilometre (km)
(pursuit distance),
28
kilometre (km)
There are several (
16-9
) kilometers, that is, the time required for pursuit. Column type
2
eight
÷
(
16-9
)
=4
(hours)
2. A car traveled 5/7 distance from A to B..
It's 80 kilometers from B.
How many kilometers is it between A and B?
2/7=80, then 80/(2/7)=280.
Third step
Every hour, a boat sails along the river from place A to place B.
28
kilometre (km)
, to the second place, and the current.
Sail back to a place. Go against the current instead of downstream.
2
Hour, known hourly water velocity
four
How many kilometers is there between Party A and Party B?
Analysis: This question first needs to know the speed and time needed to go with the water, or the speed and time needed to go against the water. Given the downstream speed and current
Speed, so it is not difficult to calculate the speed of water flow, but the time to travel downstream and the time to travel upstream are unknown, only that downstream is less than downstream.
2
Hours, seize this point, you can calculate the time needed from A to B, so you can calculate the distance from A to B, the formula is
284
×
2=20
(km)
2
×
2
=40
(km)
40
÷(
four
×
2
)
=5
(hours)
28
×
5= 140
(km).
4. A car travels from A to B with a speed of 28km/h and arrives in 4.5h.. If it takes 4 hours to get there, how many kilometers per hour will it take? (Solve with proportional knowledge)
28*4.5= 126
126/4 = 31.5km.