Carmine paid an electrician x dollars per hour for a 5-hour job plus $70 for parts. The total charge was $320. Which equation can be used to determine how much the electrician charged per hour?

5x = 320 + 70

5x = 320 − 70

(70 + 5)x = 320

(70 − 5)x = 320

@inkyvoyd @agent0smith @sourwing

Question

Carmine paid an electrician x dollars per hour for a 5-hour job plus $70 for parts. The total charge was $320. Which equation can be used to determine how much the electrician charged per hour?


5x = 320 + 70


5x = 320 − 70


(70 + 5)x = 320


(70 − 5)x = 320

@inkyvoyd @agent0smith @sourwing

inkyvoyd · Answer

does the 70 dollars have anything to do with the 5 hours? I mean, are the two dependent?

calculusxy · Answer

I believe that they are dependant because Carmine pays "plus" $70 for parts.

inkyvoyd · Answer

Well, in that sense they are, but I meant to say that if the number of hours increased Carmine would still only have to pay 70 dollars for parts, correct?

calculusxy · Answer

Yes

inkyvoyd · Answer

So, do you see why I don't think the third or fourth answer choice could be a possibility?

calculusxy · Answer

Wait. Sorry I misinterpreted your reply. I couldn't understand why it couldn't be.

inkyvoyd · Answer

Uhh, put another way, the 70 dollars is constant. No matter how many hours the electrician is working, that 70 dollars won't become 80 dollars and it won't become 60. The reason the third and fourth choices make absolutely no sense is because they have a variable with the 70. Ignore the other number for now. a variable with the 70 clearly indicates that the 70 could change, but we just established that it can't. Therefore the third and fourth answer chocies make no sense.

calculusxy · Answer

k

inkyvoyd · Answer

For the first two, I would just try to rewrite both equations.
1. 5x-70=320
2. 5x+70=320
which one makes more sense?