How many subsets A does R have for which A is similar to RSo

How many subsets A does R have for which A is similar to R?

Solution

For A to be similar to R A and R must have equal number of elements.

And for A that is subset of R to be similar there is only one subset .

For example if R ={a,b,c,d,e}

if A is to be similar to R and A subset of R

only one subset possible.

Thank you