Question

Chang drove 420 miles using 18 gallons of gas. At this rate, how many gallons of gas would he need to drive 357 miles?

Answer 1

15.3 gallons

Explanation:

ratio and proportion

420 miles = 357 miles

18 gallons x gallons

420 (x) = 357 (18)

x = 6426 / 420

x = 15.3 gallons

Answer 2

`\huge\boxed{15.3 \ \text{gallons}}`

Explanation:

We know that Chang drove 420 miles on 18 gallons of gas.

This can be represented as a ratio,
`\frac{\text{miles}}{\text{gallons of gas}}`.

`(420)/(18)`

We can also represent 357 miles over an unknown gas quantity as a ratio.

`(357)/(x)`

Since he uses a proportional amount of gas to his miles, we can set these two proportions equal to each other to find the value of x.

`(420)/(18) = (357)/(x)`

To find the value of x, we can use the cross products property.

`357 \cdot 18 = 6426\\\\6426 / 420 = 15.3`

So he needs 15.3 gallons of gas to drive 357 miles.

Hope this helped!