Solving equations!

[amathew]

Okay I need help with this question asking which equations are equivalent:

1. 2a-6=5+9a
2. 5a=11+12a
3. -11=7a

These are my thoughts on it:
2a-6=5+9a
(I just don't understand this one)

5a=11+12a
5a-12a=11+12a-12a
-7a=11
-7a/-7=11/-7
a=-11/7

-11=7a
-11/7=7a/7
-11/7=a ​

Can you please explain how to do the first one? Thanks.

 

[Deleted member 4993]

Okay I need help with this question asking which equations are equivalent:

1. 2a-6=5+9a

2a - 9a - 6 + 6 = 5 + 6 + 9a - 9a

-7a = 11

a = -11/7

2. 5a=11+12a
3. -11=7a

These are my thoughts on it:
2a-6=5+9a
(I just don't understand this one)

5a=11+12a
5a-12a=11+12a-12a
-7a=11
-7a/-7=11/-7
a=-11/7

-11=7a
-11/7=7a/7
-11/7=a ​

Can you please explain how to do the first one? Thanks.

.