b.) IF you can choose two fo the SAME sweet dishes
first choice 5 possibles
second choice 5 possible 5* 5 = 25 combo plates sweet
if you CANNOT choose the same dish twice
first choice 5 possibles
second choice 4 possibles 5*4 =20 sweet combo plates
c.) Similar to b but now you have 9 first choices and either 9 or 8 second choices......
d.) similar again 14 first choices and either 14 or 13 second choices .......