This is a subtraction of expression. You should remember the
rules in subtracting or adding expression. You can only add or subtract two
terms if they are similar terms which mean they have the same variable with the
same exponents.
(7x – 10) – (10x + 9)
You have to distribute the negative to the parenthesis.
7x – 10 – 10x – 9
7x – 10x – 10 – 9
-3x - 19
