In direct variation, the relationship between two variables can be expressed as \( y = kx \), where \( k \) is the constant of variation.
In this case, let \( y \) represent the number of miles the jet travels, and \( x \) represent the time in hours. The rate of the jet is given as 60 miles per hour (mph), so the equation that relates the distance traveled to the time is:
\[ y = 60x \]
To find the number of miles the jet travels in three hours, you can substitute \( x = 3 \) into the equation:
\[ y = 60(3) = 180 \]
Therefore, the jet travels 180 miles in three hours.