If you multiply 4 by 12, you get 48. There’s 48 donuts total. 48/5=9.6. The greatest number of donuts that can be put on each plate is 9.
To check it:
9 x 5 = 45— 9 is the highest number of donuts to be put on each plate, because we can’t go over 48 and each plate has to have the same amount
10 x 5 = 50—- 10 is too high because Jonah only has 48 donut’s to share not 50