I think answer should be B.

If the tens digit of 2x is 5, it means:
x is in range from 25-29.

So tens digit will be 2.

what if x is say 75?
then too 2x=2*75=150 has 5 as tenth digit.


I suppose answer is C. When we combine both the statements we get x=27

13.What is tens digit of the two-digit number x?
1) units digit of x is 7
2) tens digit of 2x is 5

(1) is clearly not sufficient; no information about the tens digit of x.

(2) tells us that x is either between 25 and 29 inclusive or between 75 and 79 inclusive. Not sufficient because we get two values for the tens digit of x: 2 or 7.

(1&2) tells us that x is either 27 or 77. Still not sufficient as the tens digit of x could be either 2 or 7.

The correct answer is E.

Ans. E

=>One's digit is 7 gives no clue about ten's digit (Ignore)
=> Ten's digit of 2x is 5 gives nothing again .. 2x it can be any number of the form _5_.

Coming 1 and 2 we have x= _7 and 2x=_54
2x can be 154 or just 54 making x 77 or 27 respectively.

No clear solution.

Are there tens digit cyclicity rules like there are for unit digits?