Question

F = { x : x is a 2- digit number , the sum of whose digit is 9 } ​

Answer 1

Step-by-step explanation:

I hope this may help you. My free fire I'd is 1114623453

Answer 2

Question :

F = { x : x is a 2- digit number , the sum of whose digit is 9 }

Answer :

F = { 18,27,36,45,54,63,72,81 }

Step-by-step explanation:

x is 2 digit number and the sum of the number is 9

So, 1+8 = 9 ; 2+7 = 9 ; 3+6 = 9 ; 4+5 = 9 ; 5+4 = 9 ; 6+3 = 9 ; 7+2 = 9 ; 8+1 =9

Hope this helps