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# A car needs 3 gallons of gas every 70 miles. how much gas would it need for 105 miles?

I tried dividing 3 gallons by 70 miles to get the miles per gallon but it docent help.

### 3 Answers by Expert Tutors

4.9 4.9 (230 lesson ratings) (230)
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Hey Alice -- half of 70 miles is 35 ... adding half to 70 gets 105mi ...

half of 3 gal is 1.5 gal ... adding half to 3 means 4.5 gal ... Best wishes, ma'am :)
Vivian L. | Microsoft Word/Excel/Outlook, essay composition, math; I LOVE TO TEACHMicrosoft Word/Excel/Outlook, essay comp...
3.0 3.0 (1 lesson ratings) (1)
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Hi Alice;
(3 gallons)/(70 miles)=(x gallons)/(105 miles)
Please note, both sides are in the units of gallons/miles.  These cancel.
(3 gallons)/(70 miles)=(x gallons)/(105 miles)
3/70=x/105
We are now ready to perform calculations.
Let's multiply both sides by 105...
(105)(3/70)=(x/105)(105)
4.5=x
The car needs 4.5 gallons.
Ralph L. | Algebra I, II, Visual Basic, Beginning C++ tutorAlgebra I, II, Visual Basic, Beginning C...
4.0 4.0 (1 lesson ratings) (1)
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(3 gallons/70 miles) * 105 miles
(315 gallons * miles) / 70 miles

315 gallons/70 = 4.5 gallons.