15*(a-4)=42+8*(a-4)
15a-60=42+8a-32
15a-8a=42-32+60
7a=70
a=10
(y+1)*18=36+12*(y+1)
18y+18=36+12y+12
18y-12y=36+12-18
6y=30
y=5
(k+5)*7-54=(k+5)*4
7k+35-54=4k+20
7k-4k=20-35+54
3k=39
k=13
17*(c-2)-36=19+(c-2)*12
17c-34-36=19+12c-24
17c-12c=19+34+36-24
5c=65
c=13