Help with a couple math questions...

Test Preparation
1

<h1>3: The digits of the positive three-digit integer "n" are 7, 8, and 9. How many possibles values are there for "n?"</h1>

<p>A: Three
B: Four
C: Six
D: Eight
E: Nine</p>

<h1>4:In the figure above, ∠WOY and ∠XOZ each have measure 80°. If "r" = 45, what is the value of "t?"</h1>

<p>Hyperlink: <a href="http://i584.photobucket.com/albums/ss284/sear_squid/May2010pg6.png%5B/url%5D"&gt;http://i584.photobucket.com/albums/ss284/sear_squid/May2010pg6.png&lt;/a&gt;&lt;/p>

2

<p>Answer choice for #4:</p>

<p>A: 125
B: 80
C: 55
D: 50
E: 45</p>

<p>PLEASE INCLUDE ANSWER DESCRIPTIONS!!!</p>

3

<h1>3: six.</h1>

<p>There are three possibilities for the 100s digit, two for the 10s digit (because whatever you select for the 100s digit can’t be the 10s digit), and one for the 1s digit (because neither the 100s digit nor the 10s digit can be the 1s digit). Then multiply the possibilities: 3<em>2</em>1=6.</p>

<p>Or, just list them, starting with 7 as the 100s digit:</p>

<p>789 or 798
879 or 897
987 or 978</p>

<h1>4: 45 degrees. If r=45 and m WOY is 80, then s=35. And if s=35 and m XOZ is 80, then t=45.</h1>