Addison studies a tarantula that is 30 mm long suppose she uses a microscope to magnify the spider by 4×10 to the second power how long will the spider appear to be

The microscope magnifies things by 4 * 10 to the second power, which is 4 * 100. It means it magnifies things 400 times.

If the spider's lenght is 30 mm normally, under such microscope he will appear to be 30 * 400 = 12000 mm (which is 1200 cm or 12 m).

Just a second zzz