Let's begin by listing out the information given to us:
a.
Henry:
[tex]\begin{gathered} x=0;y=15miles \\ x=2hours;y=31miles \end{gathered}[/tex]Tasha:
[tex]\begin{gathered} y=5x+25 \\ \text{when time is 0 hours (at the beginning), we have:} \\ x=0 \\ y=5(0)+25=0+25=25miles \\ \text{when time is 2 hours, we have:} \\ x=2 \\ y=5(2)+25=10+25=35miles \end{gathered}[/tex]As such, Tasha's balloon was farther from the town at the start than Henry's balloon (it was farther by 10 miles)
b.
After 2 hours, their balloon had travelled this far:
[tex]\begin{gathered} Henry\colon31-15=16miles \\ Tasha\colon35-25=10miles \end{gathered}[/tex]Therefore, Henry's balloon travelled faster than Tasha's balloon