Level 3
Xavier had 66 marbles. He packed them into packets of 4 or 6. There were 4 more packets of 4 than packets of 6. How many packets of marbles were there in the end?
Level
There are some trucks and motorbikes. There are 9 more motorbikes than trucks. The total number of truck wheels is 20 more than the total number of motorbike wheels.
How many motorbikes are there?
How many more trucks are needed in order to get a total of 172 wheels?