<p>[x]--->0 1 2
[y]--->10 a b</p>
<p>THe values of x and y in the table above are related so that (y-1) is directly proportional to (x+1).What is the value of b-a?</p>
<p>is the answer 9?</p>
<p>yes ! 
can u tell me how?THANKS!!!</p>
<p>Alright, we know that (x+1) is directly proportional to (y-1). A direct proportion is xk=y where k is a constant, right? So we know enough to solve.</p>
<p>For the first pair (y=10, x=0) we know that</p>
<p>(x+1)k=(y-1)
plug in y=10 and x=0
(0+1)k=(10-1)
1k=9
k=9</p>
<p>The constant stays the same for the other pairs so lets plug it in.
(x+1)k=(y-1)
(1+1)(9)=(a-1)
(2)(9)=a-1
18=a-1
19=a</p>
<p>plug it in to find b too.</p>
<p>(x+1)k=(y-1)
(2+1)(9)=(b-1)
(3)(9)=(b-1)
27=b-1
28=b</p>
<p>b-a
28-19
=9 </p>
<p>=)</p>
<p>(how do you make green smiley face???)</p>
<p>thanks a LOT! so xk=y is something that i MUST know to solve this problem right?</p>
<p>btw,the green face is made by typing “:” and “D” . just put them both together.</p>
<p>: + D = :D</p>
<p>yeah, you need to know xk=y. (unless there’s some other way to do it that i don’t know of??)</p>
<p>:D</p>