Colin is 9 years older than Richard. David is 12 years younger than Richard. If the total of their ages is 93, how old is the eldest of them?

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

Which rational number could be graphed between -4 and -5

An equation where variables are used to represent known values—function notation true or false