Answer:
The nation's total wealth more than doubled between 1920 and 1929, and this economic growth swept many Americans into an affluent but unfamiliar “consumer society.” People from coast to coast bought the same goods (thanks to nationwide advertising and the spread of chain stores), listened to the same music
a constant of proportionality is a number you have to multiply x by to get y.
y=kx is the equation that expresses the proportionality of x and y
the constant of proportionality is k, so k=-5
