Solution:
Since Max picks the number of apples that Maria does but squared, then Max picks 3^2=3 * 3=9 apples. Since Molly picks the number of apples that Maria picks plus the number that Max picks, Molly picks 3+9=12 apples. Finally, Mitch picks the number Molly picks squared plus the number Maria picks, so Mitch picks 12^2+3=12 * 12 +3=144+3=147 apples.