5
algebra

A train travels 60 mph. A second train leaves 1 hour later traveling 80 mph. How long until the second train catches the first?

A

2

B

3

C

5

D

4

Correct Answer: B

Choice Ahoice D is the correct answer.

  1. Define: Time for 2nd train = tt. Time for 1st = t+1t+1.
  2. Distance Equal: 80t=60(t+1)80t = 60(t + 1)
  3. Simplify: 80t=60t+6080t = 60t + 60
  4. Subtract 60t: 20t=6020t = 60
  5. Divide by 20: t=3t = 3
  6. Verify: 80(3)=24080(3)=240, 60(4)=24060(4)=240 ✓

Choice Ahoice C is incorrect because calculation error.

Choice Ahoice D is incorrect because calculation error.

Choice Ahoice C is incorrect because calculation error.

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Linear Functions Set 32