Question 316786
The 20 miles north from her house and the 75 miles east from her house are legs of a right triangle. 
The hypotenuse of the right triangle is the distance from the radio station and its range.
Use the Pythagorean theorem,
{{{20^2+75^2=D^2}}}
{{{D^2=400+5625}}}
{{{D^2=6025}}}
{{{D=sqrt(6025)}}}
{{{D=5sqrt(241)}}} or approximately,
{{{D=77.6}}}miles