DS -GMAT Prep2 - 2

Question

Please try to solve it. I am taking the test very, very soon!

Thanks!!!

riverripper · Answer

x equals 23 cent pencils
y equals 21 cent pencils

x + y = 6
x = 6-y

23x + 21y = 130

23x + 21(6-x) = 130

23x + 126 - 21x = 130

23x - 21x = 4

2x = 4

x = 2

two 23cent pencils.

alwaysfearless · Answer

Also
x+y=6
23x+21Y=130 
Miltiply 1st Eqn with 21 and minus it from the 2nd. We get x=2

kevincan · Answer

This is data sufficency, not problem solving. (2) by itself is sufficient. Note that 130/21 yields a remainder of 4.

F75 · Answer

Hello Kevincan, can you explain your post: "Note that 130/21 yields a remainder of 4".

Thanks.


My answer is also B:
23x+21y=130

I work with the unit digits (3, 1, 0) of 23, 21 and 130:
If x=1 then y must be 7 because 3*1 + 1*7 = 10 Not ok because result is 170,
If x=2 then y must be 4 because 3*2 + 1*4 = 10 ok because result is 130
If x=3 then y must be 1 because 3*3 + 1*1 = 10 Not ok because the result is too small

Then x=2, y=4.

DS -GMAT Prep2 - 2

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