Question

A & B share the cost in a ratio of 7:2. A pays £126, how much does B pay?

Answer 1

₤ 36

Explanation:

The sum of the 'parts' of the ratio = 7 + 2 = 9

Of which A pays 7 of the parts and B, 2 of the parts.

Since A pays 7 parts then 1 part = ₤126 ÷ 7 = £18

Hence 2parts `=2xx£18=£36`

Thus B pays £36

As a check : Total paid = £126 + £36 = £162

and £162 ÷ 9 = £18

Answer 2

B pays £36.00

Explanation:

Using ratio in the format of a fraction.

`("Payment by A")/("Payment by B") =7/2=(£126)/B`

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Turning it upside down (makes it easier to determine B)

`2/7=B/126`

`color(white)(.)`
,........................................................
Multiply both sides by `color(blue)(126)`

`color(brown)(2/7color(blue)(xx126)" "=" "B/126color(blue)(126))`

`color(white)(.)`

`252/7" "=" "Bxx126/126`

,.............................................................
`color(white)(.)`

But `126/126=1 " so "Bxx1 = B` giving:

`color(white)(.)`

`B=252/7 = 36`

B pays £36.00