Question

How do you solve `\frac{r + 1}{3} = \frac{5}{7}`?

Answer 1

`r=color(green)(8/7) or color(green)(1 1/7)`

Explanation:

Given
`color(white)("XXX")(r+1)/3 = 5/7`

Multiply both sides by `3xx 7`
`color(white)("XXX")7xx(r+1) = 3xx(5)`
(multiplying both sides of an equation by the product of the denominators of the two sides is sometimes called "cross multiplying")

`color(white)("XXX")7r+7 =15`

`color(white)("XXX")7r = 8`

`color(white)("XXX")r=8/7`