Question 13739
13-(2c+2)=2(c+2)+3c
13-2c-2={{{2*c+2*2+3c}}}
-2c+13-2=2c+4+3c
-2c+11=2c+3c+4
-2c+11=5c+4
-2c-5c=4-11
-7c=-7
{{{(-7c)/(-7)=(-7)/(-7)}}}
c=1

Check: Substitute c = 1 to equation
13-(2(1)+2)=2(1+2)+3(1)
13-(2+2)=2(3)+3
13 - 4 = 6 + 3
9 = 9 (Q.E.D)


0.7(3x+6)=1.1-(x+2)-------->multiply with 10
7(3x+6) = 11 - 10x - 20
{{{7*3x+7*6 =-10x+11 - 20}}}
{{{21x+42=-10x-9}}}
{{{21x+10x=-9-42}}}
{{{31x=-51}}}
{{{31x/31=-51/31}}}
{{{x=-51/31}}}

Check:
0.7(3x+6)=1.1-(x+2)
{{{(7/10)(3x+6)=11/10-(x+2)}}}
{{{(7/10)(3*(-51/31)+6)=11/10-((-51/31)+2)}}}
{{{(7/10)(-153/31)+186/31)=11/10-((-51/31)+62/31)}}}
{{{(7/10)((-153+186)/31)=11/10-((-51+62)/31)}}}
{{{(7/10)(33/31)=11/10-(11/31)}}}
{{{(7*33/10*31)=(11*31-11*10)/(10*31)}}}
{{{231/310=(341-110)/310)}}}
{{{231/310=231/310}}}  (Q.E.D)

OK