Carla is renting a canoe. it costs $80 for 2 hours and 120 for 4 hours. what is the rate of change for this situation?

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

What is the frequency of the sinusoidal graph?

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.