Look at the picture.

The base of the ladder is 6.47 feet from the house.
Alright here I go:
9.98 * 10^6 in standard form is 9,980,000
7.3 * 10^7 in standard form is 73,000,000
73,000,000 subtracted by 9,980,000 is 63020000.
63020000 in scientific notation is 6.302 * 10^7
Hope I helped!
It has 3 sig figs because 0 is not significant in this case because it’s at the end