Mai has been walking indoors because of cold temperatures. On Day 4 at noon, Mai hears a report that the temperature is only 9 degrees Fahrenheit. She remembers
the morning news reporting that the temperature had doubled since midnight and
was expected to rise 15 degrees by noon. Mai is pretty sure she can draw a diagram
to represent this situation but isn't sure if the equation is 9 = 15 + 21
or 2(1 + 15) = 9. What would you tell Mai about the diagram and the equation and
how they might be useful to find the temperature, 1, at midnight?