If x = 2
First we need to multiply out the brackets.
To do this we need to multiply what's inside the brackets by 3, as this is the number next to the bracket - meaning it needs to be multiplied.
This makes 3x+12
Here we can figure out the value of 3x - which means 3 multiplied by x, which is 6.
6 + 12 is 18.
18 is the value of 3(x+4)
Hope this helped :)