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

1 Answer
Apr 16, 2016

y - 19

Explanation:

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

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

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

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

Combine like terms:
(4y - 3y) = y
(-9 - 10) = -19

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