Question #804b8

1 Answer
Nov 16, 2017

Let, the blank number be #x#
Then,
#8/10+x=1#
Note- 1 can also be written as #1/1,2/2,3/3,.....,10/10#
Using that
#8/10+x=10/10#
Subtract #8/10# from both sides
#cancel(8/10)cancel(+8/10)+x=10/10-8/10#
#x=(10-8)/10#
Solve
#x=2/10#
Simplify
#x=(cancel2^1)/(cancel(10^5)#
#x=1/5#