The average of 5 two digit numbers is 60.X and Y are two of the 5 numbers.If the digit of each of X and Y are interchanged then the average of the five numbers will be 51.Instead of this ,if the other numbers are multiplied by -1,then the average of the five numbers will be -18.Find the sum of the tens digit of X and Y.

1) 10
2) 11
3) 12
4) 13

• 1)10
  Let the two digits of x be a and b and digits of y be c and d. So,
  10a+b+10c+d+p+q+r=300
  10b+a+10d+c+p+q+r=255
  
  and by solving above two equations we will get a-b+c-d=5-----(1)
  
  and from the 3rd condition we will get that x+y-p-q-r=-90
  by solving that 10a+10c+b+d=105------(2)
  
  by adding (1) and (2)
  we will get 11(a+c)=110
  therefore,a+c=10
• 4 years agoHelpfull: Yes(0) No(0)