Two cars

From A town started two cars to town B. The first begins at 7:00 at an average speed of 60 km per hour. The second car starts at 10:00 at an average speed of 100 km per hour. The first car will not stay in B, and on the way back, meet the second car halfway from A to B. At what time will they meet in hours?

Result

t = 10:45 h

Step-by-step explanation:

1.5 s = 60(t-7)
0.5 s = 100(t-10)


1.5·s = 60·(t-7)
0.5·s = 100·(t-10)

1.5s-60t = -420
0.5s-100t = -1000

Row 2 - 0.5/1.5 · Row 1 → Row 2
1.5s-60t = -420
-80t = -860


t = -860/-80 = 10.75
s = -420+60t/1.5 = -420+60 · 10.75/1.5 = 150

s = 150
t = 43/4 = 10.75

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