Question

How do you solve `3( 0.04- 2.1x ) = 7.2`?

Answer 1

See a solution process below:

Explanation:

Step 1) Divide each side of the equation by `color(red)(3)` to eliminate the need for parenthesis:

`(3(0.04 - 2.1x))/color(red)(3) = 7.2/color(red)(3)`

`(color(red)(cancel(color(black)(3)))(0.04 - 2.1x))/cancel(color(red)(3)) = 2.4`

`0.04 - 2.1x = 2.4`

Step 2) Subtract `color(red)(0.04)` from each side of the equation to isolate the `x` term while keeping the equation balanced:

`-color(red)(0.04) + 0.04 - 2.1x = 2.4 - color(red)(0.04)`

`0 - 2.1x = 2.36`

`-2.1x = 2.36`

Step 3) Divide each side of the equation by `color(red)(-2.1)` to solve for `x` while keeping the equation balanced:

`(-2.1x)/color(red)(-2.1) = 2.36/color(red)(-2.1)`

`(color(red)(cancel(color(black)(-2.1)))x)/cancel(color(red)(-2.1)) = -1.124`

`x = -1.124` rounded to the nearest thousandth.