\(V= \frac{S}{t}\)
\(t= \frac{S}{V}\)
\(t= \frac{S}{c}\)
\(t= \frac{6.1*10^{12}}{299792458}\)
\(t=20347.4098071s\)
It takes 20347.4098071s for light from the sun to reach Pluto.
The 6.110^9 is replaced by 6.110^12 on line 4 because we convert the distance from km to m.
c = speed of light. If a different value was given in the previous question then use that instead of the value I used to do the final calculation.
