The number 645,300 is is already in the expanded form. I think what you mean is in specific notation, because in this form, we make use of exponents. To convert this, simply move the decimal place to the left until before you get to the last digit. The number of places moved is equivalent to the exponents, and the + sign is for movement to the right, and the - sign is for the movement to the left. Thus, the answer would be 6.453×10⁻⁵.
Let
x = the number of dimes
y = the number of quarters
The total sum is $2.05, therefore
0.10x + 0.25y = 2.05
Divide through by 0.05 to obtain
2x + 5y = 41 (1)
There are 3 fewer quarters than dimes, therefore
y = x - 3 (2)
Substitute (2) into (1).
2x + 5(x - 3) = 41
2x + 5x - 15 = 41
7x = 56
x = 8
y = x - 3 = 5
Answer: 8 dimes, 5 quarters
8 miles is the distance because you can see that the inches are the same as miles