Linear word problem.

Question

Tanisha and Rebecca are signing up for new cellphone plans that only charge for the number of minutes and everything else is included in a monthly fee. Their plans are as follows: Tanisha’s plan: $0.15 per minute used talking and a $25 monthly fee. Rebecca’s Plan: $0.10 per minute used talking and a $18.50 monthly fee. (a) Figure out after how many minutes the two plans will charge the same amount? (b) Interpret your answer. It may help to read their two plans again and think about which one you would rather pay.

Answer 1

25 + 0.15 x = 18.50 + 0.1 x

6.50 + 0.15x = 0.1x <--- subtracts 18.50 from both sides

6.50 = -0.05x <--- subtracts 0.15x from both sides

650 = -5x <--- multiplies both sides by 100

-130 = x

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