let x be the 1st digit and y be the 2nd digit
10x+y be the original no. and 10y+x be the new no.
i)x+y=11
ii)10y+x=10x+y-45 it becomes -9x+9y=-45
i)9(x+y)=11(9)= 9x+9y=99
+-9x+9y=-45
18y=54
18 18
y=3
if y=3
i)x+y=11
x+3=11
x=11-3
x=8
so the final ans. will be 83