How do you solve for r: p = 2r - 4?

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Answer 1 · 2017-05-05T12:06:59

See a solution process below:

First, add $color(red)(4)$ to each side of the equation to isolate the $r$ term while keeping the equation balanced:

$p + color(red)(4) = 2r - 4 + color(red)(4)$

$p + 4 = 2r - 0$

$p + 4 = 2r$

Now, divide each side of the equation by $color(red)(2)$ to solve for $r$ while keeping the equation balanced:

$(p + 4)/color(red)(2) = (2r)/color(red)(2)$

$(p + 4)/2 = (color(red)(cancel(color(black)(2)))r)/cancel(color(red)(2))$

$(p + 4)/2 = r$

$r = (p + 4)/2$

Or

$r = p/2 + 4/2$

$r = p/2 + 2$