THERE ARE 4 ZEPTS AND 8 Zios
At first I tried to do it in ratio but it didn't work.I would write out the timetables of three and seven and then find out numbers that give a sum of fifty-two.
Ratio does not work because (seven is to three )-the ratio- are not equal in one portion.My words may be rather confusing but if you should take time to consider my pdf you would probably get the jist of what I am saying.
You could also approximate fifty two and use times tables to help you work the main answer out.
I could not find out any corresponding ways to get fifty two and would be grateful to get another answer that doesn't match mine.
Below,I have uploaded a file that you may want to consider seeing as it should help you if you get stuck.I hope it is of help to you.
Please consider my working out as I could not think of any other way to come across the answer and would be happy to come across the method if there is any.
I hope this has come to use of you if any use.