Notoriousjae said:
People good at math please help. thanks
1. If the side length of a square is increased by 50%, the area increases by what percent?
A.125
B.225
C.25
D.50
E.75
2. If 3x+y=5 and 5x+y=6, then y=?
A.1
B.3.5
C.5/6
D.2
E.3
3. A gift of $180 is to be shared by Brett and Andrew in such a way that Andrew gets 25% more than Brett. How much does Brett get?
A.100
B.72
C.108
D.144
E.80
Answers:
1. A
2. B
3. E
(honest!)
Explanations:
1. Easiest way I think to approach these is to just plug in some numbers and see what happens. You could try and think of some equation (and for most algebra problems this may be the easiest), but it's pretty quick this way. I tried length 2 for one and length 3 for the second one. Double-checked it against 4 for one and 6 for the other square. In both scenarios, the increase is 125%. If you just run the math and compare both squares you'll see in increase. The difference comes out to be 225%, but the INCREASE is just 125%.
2. For this one just add the two together, modifying one of them to get rid of one of the unknown variables.
3x+y=5
+ 5x+y=6
-----------
Gets changed to (by multiplying the top by -1):
-3x-y=-5
+ 5x+y=6
-----------
2x = 1
So, now that you have one of the variables (x = .5), just plug it back into one of the original equations and you'll solve for y (you'll get the same answer for both).
3. You could do this a couple of ways too. One way is to just plug some numbers in. Since you know that Andrew gets %25 more than Brett and the total is 180, then we're looking for the lesser of two numbers that add up to 180. If you look through the numbers and just pick one, say start with the second largest as Kaplan at times suggests, this would give Brett 80 and Andrew what? Well, Andrew has 25% MORE than Brett. Bret has 80. 25% more than 80 is what? 100. Looks like you won't have to search any more.
A second approach (and you'll want to get very good at doing this) is to use Algebra. There are several questions in Topscore and Achiever that can explain things better than I can. Best of luck to you!
