Answer
The distance from one focus to the other focus is $~~7.20~R_S$
Work Step by Step
We can find the distance $d$ from one focus to the other focus:
$d = 2ea$
$d = (2)(0.0167)(1.50\times 10^{11}~m)$
$d = 5.01\times 10^9~m$
The distance from one focus to the other focus is $~~5.01\times 10^9~m$
We can express this distance in terms of $R_S$, the solar radius:
$\frac{d}{R_S} = \frac{5.01\times 10^9~m}{6.96\times 10^8~m}$
$\frac{d}{R_S} = 7.20$
$d = 7.20~R_S$
The distance from one focus to the other focus is $~~7.20~R_S$
