Given:
Speed: 50mph
time: 3 1/2 hour
[tex]\text{time}=3\frac{1}{2}=\frac{7}{2}\text{hour}[/tex]To find the distance:
[tex]\text{Distance}=\text{time}\times speed[/tex][tex]\text{Distance}=\frac{7}{2}\times50=175\text{ miles}[/tex]Option D is correct