Which of these systems of linear equations has no solution?
A) 2 x + 8 y = 15. 4 x + 16 y = 30.
B)2 x- y = 18. 4 x + 2 y = 38.
C)4 x + 7 y = 17. 8 x -14 y = 36.
D)4 x -3 y = 16. 8 x -6 y = 34.

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.