The distributive property is basically expanding brackets.
So if you take 3(x + 4) = 36 and remove the brackets (so multiplying out the 3), you get:
3x + 12 = 36
And from there you simplify :)
3x + 12 = 36
3x = 24
x = 8
The distributive property was used to multiply the 3 through the brackets, thus making the equation easier to solve I guess
Explanation: