14 / 1.8 = 7.77777778
about 7.77777778 miles
but it depends on what the initail fee is
5 quarters =1.25$
15$÷1.25$=12
then 15$ in quaters would weigh 12 ounces
So this equation will be
x^2 +y^2 = 16^2
hope this will help you
Note --> As you're writing 'zeroes' , I assume there is a typing mistake and you've given a Quadratic equation in the question

Hence , the roots are 1/2 and -6
The graph attached confirms the same ,
Hope it helps you :)