Help with Maths

I pride myself on understanding High School Mathematics!  However, tonight I was ambushed by two children requiring assistance and I didn't quite understand what was being asked.  Actually, it didn't quite happen that way, as it was Ian who was ambushed.  I just heard what was going on as I was madly packing my stuff for the weekend - and exercising!  I did have a look at the Year 9 assignment.   Although I could work out the answer, I wasn't sure on the method (a 'value' table!?).  Anyway, we had to get professional help!  I was very grateful to Andrew Jackson, who came over with very little notice and stayed for some time working through the two assignments.  He's a great guy!  The girls are lucky to have such a great cousin!