Answer :
[tex]t=4+\frac{d}{r} \\ \\
t=6.2 \ [h] \\
d=100 \ [miles] \\ \\
6.2=4+\frac{100}{r} \\
6.2-4=\frac{100}{r} \\
2.2=\frac{100}{r} \\
2.2r=100 \\
r=\frac{100}{2.2} \\ r=45 \frac{5}{11} \\
r \approx 45.45 \ [\frac{miles}{h}][/tex]
The average speed of the delivery truck is about 45.45 miles per hour.
The average speed of the delivery truck is about 45.45 miles per hour.