I don’t understand this can you please help me?

Which expression shows the sum of the polynomials with like terms grouped together

Seymour is twice as old as cassandra. if 16 is added to cassandra’s age and 16 is subtracted from seymour’s age, their ages become equal. what are their present ages? show !

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?