Question 248060
This looks like fun
Let a and b be the digits of a number
a+b=16
a=16-b
10(a)+b-10b-(a)=18
substitute b-16 for a
10(16-b)+b-10b-(16-b)=18
160-10b+b-10b-16+b=18
160-16-18=18b
160-34=18b
126=18b
7=b
9=a
9+7=16
original number 97 
new number 79
97-79=18