What is twenty less than twelve percent of a number minus the sum of twice the number and negative fifteen

(0.12*x - 20) - (2x + -15)

So basically here, you can write out the equation, what is twenty less

-20

Than twelve percent of a number (we have to create a variable here)

0.12x - 20

Minus 

(0.12x - 20) - 

The sum of twice the number

(0.12x - 20) - 2x

and negative fifteen

(0.12x - 20) - (2x + -15)

So to solve this, you want to open up both parenthesis, the first one is easy, and the second one, reversing all operations inside.

0.12x - 20 - 2x - -15

or 

0.12x - 20 - 2x + 15

(because two minuses equals one plus)

Now you can reorder all of the components, having them keep the sign before them

(+) 0.12x - 2x + 15 - 20

Or

-1.88x + -5

And so there we go, that's the most we can do.

(Or something I probably made a mistake at some point)