Can you show me how to solve this problem

[dude101]

Hi I'm new to Algebra and need some help. WE are trying to simplify expresions. Can somebody show me how to this one.
7-(-2y)+y-9 if y=6

 

[Daniel_Feldman]

Well, remember some things about negative numbers.

x-(-y)=x+y

-x+y=y-x

etc...


So 7-(-2y)=7+2y

7-(-2y)+y-9=7+2y+y-9

7-9=-2, and 2y+y=3y, so

7+2y+y-9=3y-2

When y=6, this expression equals

3(6)-2=18-2=16

 

[dude101]

I got it

7-(-2y)+y-9 if y=6
(-2y)+y=-3y
7-9+=-2
3y+-2=16
I was makeing (-2y)+y=-1

 

[dude101]

THank you Daniel

for your help

 

[Denis]

7-(-2y)+y-9 if y=6

well, you can always substitute right off the bat:
7- (-12) + 6 - 9 = 7 + 12 + 6 - 9 = 16