Please help me using product rule

Suppose investors can earn a return of 2% per 6 months on a treasury note with 6 months remaining until maturity. the face value of the t-bill is $10,000. what price would you expect a 6-month maturity treasury bill to sell for? (round your answer to 2 decimal places. omit the "$" sign in your response.)

Which ordered pair (c,d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

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.