Question

How do you solve `2.1x-5=7.7`?

Answer 1

`x=6.05`

Explanation:

so this is our equation `2.1x-5=7.7`
so we are meant to leave `x` alone to find the value of `x`

add `5` on both sides and you get `2.1x=12.7`

then divide `2.1` on both sides and you get `x=6.047619048`

round it to `2` decimal places and you get `x=6.05`

Proper working shown below:-

`2.1x-5=7.7`

`2.1x=12.7`

`x=6.05`

Answer 2

`x = 6.05`

Explanation:

first, you want to isolate `x` by adding 5 to both sides

`2.1x - 5 = 7.7`

`2.1x = 12.7`

divide both sides by 2.1 to see what `x` is worth

`x = 6.0476` (or `6.05` rounded)

Answer 3

A trick to get round the decimals giving you a problem

`x=127/21~~6.05` to 2 decimal places

Explanation:

Multiply all of both sides by 10

`21x-50=77`

Add 50 to both sides

`21x=127`

Divide both sides by 21

`x=127/21=6.047619....`

If you round off the answer you end up with an imprecise solution.

ONLY ROUND OFF IF INSTRUCTED TO

So we need a precise solution that involves the least work thus we stick to the fraction format.

`x=127/21 ->6 1/21`

However, the structure adopted for the question is 1 decimal place so to cover ourselves we can write

`x=127/21~~6.05` to 2 decimal places

The `~~` means 'approximately equal to'

ALWAYS STATE THE NUMBER OF DECIMAL PLACES ROUNDED TO