Answer:
42
Explanation:
S1 let a and b be the digits of the number
so a 2 digit number cab written as - 10×a + b
eg - 68 as 6×10 + 8
S2 ) according to ques
a + b = 6 - eqn 1
(10×a + b) - (10×b + a) = 18
9×a - 9×b = 18
a - b = 2 - eqn 2
S3)from eqn 1 and eqn 2
we get a = 4 and b = 2
hence number is 42