# How do you simplify (4y-9)-(3y+10)?

Apr 16, 2016

$y - 19$

#### Explanation:

A place where students commonly make mistakes with is the terms after the subtraction sign, in this case $3 y + 10$.

Pretend that there is a negative 1 in front of $\left(3 y + 10\right)$. So you would have: $- 1 \left(3 y + 10\right)$

Distribute that negative one to the terms in the parenthesis, to get $- 1 \left(3 y\right) + - 1 \left(10\right) = - 3 y - 10$

Combine that with the remaining expression and then simplify.
$4 y - 9 - 3 y - 10$

Combine like terms:
$\left(4 y - 3 y\right) = y$
$\left(- 9 - 10\right) = - 19$

Put those together to get the answer of:
$y - 19$