1) 2a = 9b ⇒ 2:9
2) a + b = 3b ⇒ a = 2b ⇒ 1:2
Answers: 2:9 and 1:2
The correct answer is 3) $15
It seems that the first row was before the fixed amount was charged.
Days 1 and 2 are in a constant change of 1x and 15y.
I'm not sure if you mean (
) or (
) I solved it both ways .

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I hope I helped you^_^
Answer:
7 hours!
Step-by-step explanation:
(3a-5) - (a+3)
Subtract a from 3a while subtracting 3 from 5
Final Answer: 2a - 8