When we multiply out brackets, everything inside the bracket gets multiplied by whatever is outside the bracket.
Take care with the signs remembering the rules about multiplying negative numbers.
The following examples show how the 3 and the -5 outside the brackets affect the terms inside the brackets.
Multiply out the brackets and simplify by collecting like terms.
3(4x - 2) - 5(2x + 3)
From the explanation above we get
12x - 6 - 10x - 15
Now collect the x terms to get 2x and the numbers to get -21
The answer is 2x - 21