Question

Rico, Carolina, and Gloria have pizza that they are going to be sharing with other people. Rico gave away 1/3 of his cheese pizza to Carolina and she gave him 3/7 of her pepperoni. Rico then gave Gloria 1/7 of his cheese pizza. How much pizza, pepperoni and cheese, does Rico have now?

Answer 1

We know that

[cheese pizza, that does Rico have now]
=1-(1/3)-(1/7)
=(21-7-3)/21
=11/21

[pepperoni pizza, that does Rico have now]
=3/7----> multiply by (3/3)------> 9/21

total pizza (pepperoni + cheese) that does Rico have now
=11/21+9/21------> 20/21----> 95.2% of one pizza

the answer is
20/21