<p>If (x+y)^2 - (x-y) ^2 = 84 and x and y are positive integers, which of the following oculd be the value of x + y?</p>
<p>A. 10
B. 12
C. 14
D. 16
E. 18
Answer is A</p>
<p>A gas tank with a capacity of 18 gallons is empty. A pump can deliver g gallons every t seconds. In terms of g and t, how many seconds will it take this pump to fill the tank?</p>
<p>A. 18t divided by g
B. 18g divided by t
C. 18gt
D. g divided by 18t
E. gt divided by 18</p>
<p>Answer is A</p>
<p>There is a circle graph with 15% financing, 25% insurance, 10% maintenance, 3% fees, 10% fuel, 35% depreciation, 2% repairs</p>
<p>Tracy purchased a new car. For the first five yeras, she is responsible for all costs except insurance, which her parents are paying. If all her costs are typical, as shown in the graph, then maintenance represents what percent of the costs for which she is responsible?</p>
<p>A. 7.5%
B. 10%
C. 12.5%
D. 13 1/3%
E 15%</p>
<p>answer is D</p>
<p>1.)(x+y)^2 - (x-y) ^2 = 84</p>
<p>Just foil it out…</p>
<p>(x^2 + 2xy + y^2) - (x^2 - 2xy + y^2) = 84
2xy + 2xy = 84
4xy = 84
xy = 21</p>
<p>x=3, y=7 therefore x+y = 10 [A]</p>
<p>The key to this problem is just foiling it out correctly (remember to distribute the minus sign). Also, remember xy = 21 means that two numbers multiplied together is 21.</p>
<p>2.) A gas tank with a capacity of 18 gallons is empty. A pump can deliver g gallons every t seconds. In terms of g and t, how many seconds will it take this pump to fill the tank?</p>
<p>Lets say g = 2, t = 1</p>
<p>That means the tank will fill up in 9 seconds. So now we can plug g=2, t=1 into the answer choices. The number better be 9.</p>
<p>A works
B fails
C fails
D fails
E fails</p>
<p>This is the fastest method, and is pretty straightfoward.</p>
<p>3.) There is a circle graph with 15% financing, 25% insurance, 10% maintenance, 3% fees, 10% fuel, 35% depreciation, 2% repairs</p>
<p>Tracy purchased a new car. For the first five yeras, she is responsible for all costs except insurance, which her parents are paying. If all her costs are typical, as shown in the graph, then maintenance represents what percent of the costs for which she is responsible?</p>
<hr>
<p>Lets say she has to pay 100 dollars all together. That means that 10/75 x 100 goes to maintenance. She has to pay $13.33 to maintenance out of a total $100 paid, thus 13.33% goes to maintenance. [D]</p>