Hello.
First of all, solve 5(c+2) by applying the distributive property.
I mean, 5*c and 5*2
So rewrite:
3c - 2 = 5c + 10
Now, you have to solve for c and then move all the Cs to the left of equal and change them sign, same to all known terms but move them to the right instead!
3c - 5c = 10 + 2
-2c = 12
The c can't be negative so divide both terms for -1
2c = -12
divide both terms for 2
2c/2 = -12/2
c = -6