How to specify limit and offset in array in rails?

I have 3 tables PostText, PostImage and PostVideo. now I am Combining data from all the above three table into a single array called userposts.

Now from userposts I want to access only 10 records starting with offset 15.

How can I do that?

I tried out userposts.first(10). It gives me first 10 recordes but I want 10 recordes starting from offset-15.

Please help me.

thanks in advance.