1) 3(2a-5)=12-7a
First distribute the 3. This leaves you with 6a-15=12-7a.
Now, add 15 to both sides. This leaves you with 6a=27-7a.
Now, add 7a to both sides. This leaves you with 13a=27.
Now, you can finally divide 13a on both sides. This leaves you with a=27/13
2) 27=3c-3(6-2c)
First, distribute the 3.This leaves you with 27=3c-18+6c
Now, combine like terms/simplify. This leaves you with 27=9c-18.
Now, add 18 to both sides. This leaves you with 45=9c.
Now, you can finally divide 9 on both sides. This leaves you with 5=c.
Lastly, use the reflexive property. This leaves you with c=5.
3) 6c-8-2c=-16
First, combine your like terms. This leaves you with 4c-8=-16.
Now, add 8 to both sides. This leaves you with 4c=-8.
Now, divide 4 on both sides. This leaves you with c=-8/4.
Finally, you can simplify the fraction. This leaves you with c=-2.
Comment if you have any questions!