options: Solve real-world and mathematical problems involving the four operations with rational numbers. (Computations with rational numbers extend the rules for manipulating fractions to complex fractions.)

Apply and extend previous understandings of addition and subtraction to add and subtract rational numbers; represent addition and subtraction on a horizontal or vertical number line diagram.

Apply and extend previous understandings of multiplication and division and of fractions to multiply and divide rational numbers.
problem_activity: A red-throated loon is a type of diving bird that dives for its food. One particular loon dives for 8 seconds to a depth of 12 feet under the surface of the water.
a.   Assume the loon dives at a constant rate. Write an equation that can be used to represent the elevation,
$$y$$
, of the loon after
$$x$$
seconds into the dive.
b.   If the loon is at a depth of 22.5 feet under the surface of the water, how long was it diving for?


correct_option_index: 2