help with these two math problems? and i need to see the work for it too?

Question

Add:
(-15rs + rst ) + (5rs - rst )

Subtract:
(7c - d) - (3c - 2d)

Answer 1

1. (-15rs + rst ) + (5rs - rst)

First: eliminate parenthesis - rewrite the expression.

-15rs + rst + 5rs + (- rst)
-15rs + rst + 5rs - rst

Sec: combine "like" terms.

-15rs + 5rs + rst - rst
-10rs + 0rst
-10rs

2. (7c - d) - (3c - 2d)

First: eliminate parenthesis - rewrite the expression.

7c - d - (3c) - (- 2d)
7c - d - 3c + 2d

Sec: combine "like" terms.

7c - 3c - d + 2d
4c + d

Answer 2

The first problem: (-15rs + rst ) + (5rs - rst )
Remove the parentheses: -15rs + rst + 5rs - rst
Rearrange terms: -15rs + 5rs + rst - rst
Combine similar terms: -10rs + 0 = -10rs

You can solve the second problem the same way.

Answer 3

(-15rs +rst) + 5rs - rst
15rs + rst + 5rs -rst
15rs + 5 rs
20rs

(7c -d) - (3c - 2d)
7c -d -3c + 2d
4c + d

http://www.coolmath.com
"like terms"
Terms are separated by + and -.
Like terms have the same letters with the same exponents.

Answer 4

The parentheses are meaningless in this context. Just eliminate them. Then add the terms that are alike.
-15rs + 5rs + rst -rst = -10rs
7c - 3c - d + 2d = 4c + d

Or you could view it like this
-15rs + rst
5rs - rst
----------------
-10rs + 0rst

Answer 5

-15rs + rst + 5rs -rst = -15rs + 5 rs + rst - rst = -10rs
7c - d - 3c -(-2d) = 7c - 3c -d + 2d = 4c + d

Answer 6

(-15rs + rst ) + (5rs - rst )

= -15rs + rst + 5rs - rst

= -10rs

(7c - d) - (3c - 2d)

= 7c - d - 3c + 2d

= 4c + d

Answer 7

(-15rs + rst ) + (5rs - rst )=(-15rs + 5rs ) + (rst - rst )= -10rs
(7c - d) - (3c - 2d)=7c - d - 3c + 2d = (7c - 3c)+ ( -d+ 2d)=4c+d

Answer 8

Add or subtract "things" that are the same:-
Question 1
- 10 rs
Question 2
= 4c - d + 2d
= 4c + d

Answer 9

-10rs

4c+d