Multiplying Out Brackets

Salami asked the following:

Question: 6 (2x - 3) = 42

Multiplying out brackets ... - 6 × 2x = 12x
6 × -3 = -18

= 12x + -18
= 12x - 18
= -6x
-6x = 42
42/-6 = -7
x = -7

Have I gone completely wrong? I don't really understand. :(

Thanks for this, Salami! You have done very well, but the answer is a big YES! Hopefully some others will have spotted it too.

Here's where you went wrong:

= 12x - 18
= -6x

You treated 12x - 18 as 12x - 18x.

Let's try again: 12x - 18 = 42 (it really IS useful to work on the whole expression, not just bits of it!)

Now you must simplify the expression by adding 18 to both sides:

12x - 18 + 18 = 42 + 18

This becomes: 12x = 60 which simplifies to: x = 5

You can now check this is correct: 6 (2x - 3) = 42 ... 6 (2×5 - 3) = 42 ... 6 (7) = 42 ... which is correct.

So 42 really is the answer to life, the universe and everything!