0.02 in scientific notation with negative powers of 10

2 x 10⁻²

I place ⁻² as the negative powers of ten because I counted two places from the original position of the decimal to the number 2. The direction from the decimal is going to the right.

The negative or positive powers of ten determined by the direction of the decimal point. If it moves to the right then it is negative. If it move to the left then it is positive.

For example.  2000 in scientific notation.
The decimal point is located after the 3rd zero. According to the rule of scientific notation, only one digit must remain before the decimal point, Thus, 2000 is 2.000
The decimal point moved three place to the left from its original position. So its power of ten is positive three.

2000 = 2 x 10³

The answer is 225 miles per 4.5 hours. hope this ; )