Answer
$y=25.4p-118$
When recovery level is $ 70\%$, the economic value is $ {{\$}} 1660$ billion.
Work Step by Step
The regression line is
$\qquad y=mx+b$,
where $m$ and $b$ are computed as follows.
$m=\displaystyle \frac{n(\sum xy)-(\sum x)(\sum y)}{n(\sum x^{2})-(\sum x)^{2}}\qquad b=\frac{\sum y-m(\sum x)}{n},$
$n=$ number of data points.
$\left[\begin{array}{lllll}
& p & y & py & p^{2}\\
& & & & \\
\hline & 10 & 200 & 2000 & 100\\
& 40 & 900 & 36,000 & 1600\\
& 50 & 1000 & 50,000 & 2500\\
& 80 & 2000 & 160,000 & 6400\\
\hline & & & & \\
\sum & 180 & 4100 & 248,000 & 10,600\\
& & & &
\end{array}\right]$
$m=\displaystyle \frac{4(248,000)-(180)(4100)}{4(10,600)-(180)^{2}}=\frac{127}{5}=25.4$
$b=\displaystyle \frac{4100-(25.4)(180)}{4}=-118$
$y=25.4p-118$
When $p=70$ (percent),
$y=25.4(70)-118=1660$
