Steven has 18 peaches. Jake has 12 fewer peaches than Steven who has 8 more peaches than Jill. How many peaches does Jill have?
Let's denote Steven's number of peaches by s, Jake's number of peaches by j, and Jill's number of peaches by i. 

Then we have the following system of equations: 

s=18, 
s=j+8, 
j=s-12. 

From the first equation we get that 

s=18 

Substituting this value of s into the second equation we get that 

18=j+8 

Therefore 

j=10 

Substituting this value of j into the third equation we get that 

j=s-12 

Therefore 

i=18-12=6