Let's begin by identifying key information given to us:
Entry fee = $15 /pair pf people
10 tabs = $0.01
Eva = 7,100 tabs
Brian = 1,300 tabs
The entry fee is $15 for a pair
We will convert this to tabs, we have:
[tex]\begin{gathered} 10tabs=$0.01$ \\ x=15 \\ \text{Cross multiply, we have:} \\ 0.01(x)=10\cdot(15) \\ 0.01x=150 \\ x=\frac{150}{0.01}=15,000 \\ x=15,000tabs \end{gathered}[/tex]Eva & Brian have gathered a total of 8,400 tabs. The number of tabs they need to collect to meet their target is given by the diffence between 15,000 & 8,400
[tex]\begin{gathered} =(15,000-8,400)_{}tabs \\ =6,600tabs \end{gathered}[/tex]Therefore, D (6,600) is the correct answer