Pencils sell for 1.98 per dozen a teacher bought 288 pencils for his math classes. how much did the pencils cost?

Can any one me with the answers to these questions asap?

Is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis.

Given the following linear function sketch the graph of the function and find the domain and range. ƒ(x) = -5x + 4