Well,
If we approximate the speed of light as 300,000,000 m/s, then we just have to multiply 300,000,000 by 1.25.
300,000,000 * 1.25 = 375,000,000 meters
I would put it in scientific notation.
3.75 * 10^8 meters
If you want it in miles, then we can approximate the speed of light as 186,000 m/s. Just do the same thing.
186,000 * 1.25 = 232,500 miles
Scientific notation: 2.325 * 10^5
