Question

John can drive 240miles at the same time as it takes george to drive 220 miles if john drives 5mph faster than george then how fast does john drive?

Answer 1

John drives `30` miles per hour

Explanation:

Let
`color(white)("XXX")J =` John's driving speed (in miles per hour)
`color(white)("XXX")G =` Georges' driving speed (in miles per hour)

For a certain amount of time, `t`, we are told:
[1]`color(white)("XXX")t=240/J`
[2]`color(white)("XXX")t=200/G`
and also that
[3]`color(white)("XXX")J=G+5`
`rArr`[4]`color(white)("XXX")G=J-5`

Combining [1] and [2]
[5]`color(white)("XXX")240/J=200/G`
`rArr`[6]`color(white)("XXX")200J=240G`

Substituting `(J-5)` from [4] for `G` in [6]
[7]`color(white)("XXX")200J=240(J-5)`
`rArr`[8]`color(white)("XXX")200J=240J-1200`
`rArr`[9]`color(white)("XXX")40J=1200`
`rArr`[10]`color(white)("XXX")J=30`