A given number C is between 10 and 99 and has the property that if its digits are reversed, the difference between Creverse and C = 36. Furthermore, 3 times the second digit minus 2 times the first digit = 15. What is C's second digit?
options:
A) 2
B)3
C)4
D)6
E)7
OA IS E
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C's second digit
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pappueshwar
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Let T = the tens digit and U = the units digit.pappueshwar wrote:A given number C is between 10 and 99 and has the property that if its digits are reversed, the difference between Creverse and C = 36. Furthermore, 3 times the second digit minus 2 times the first digit = 15. What is C's second digit?
options:
A) 2
B)3
C)4
D)6
E)7
OA IS E
C = 10T + U.
C reversed = 10U + T.
The difference between C reversed and C is 36:
10U + T - (10T + U) = 36
9U - 9T = 36
9(U-T) = 36
U-T = 4.
U-4 = T.
3 times the second digit minus 2 times the first digit is 15:
3U - 2T = 15.
Substituting T=U-4 into 3U - 2T = 15, we get:
3U - 2(U-4) = 15
U + 8 = 15
U = 7.
The correct answer is E.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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