there was some information lost when these images were scanned in and so some of the answers
do not correspond to what appears as the problem... so here are the corrections and the worked
out solutions...

#11)

-7x -5(x-2) = 8
distribute
-7x -5x+10 = 8
collect
-12x + 10 = 8
-10 on both sides
-12x = -2
div by -12 on both sides
x = 1/6

#7)

-1/7x -3/8 = 5/8
mult thru by lcm 56
-8x -21 = 35
add 21 to both sides
-8x = 56
divide both sides by -8
x = -7


#12)

P= 2L + 2W
L= 13 + W
substitute 46 & L into P
46 = 2(13 + W) + 2W
46 = 26 + 2W + 2W
46 = 26 + 4W
20 = 4W
5 = 2
L = 13 + 5 = 18