Lethna buys some boxes of pens and some packets of pencils.
There are 40 pens in each box. There are 12 pencils in each packet.
Lethna gives one pen and one pencil to each student in Year 7 of her school.
When she has done this she has no pens left and no pencils left.
Work out how many boxes of pens and how many packets of pencils Lethna could
have bought