Miguel spends $100 on books, five of which are hardcover and the remaining four are paperback. The prices at the bookstore are b

The total number of bills and coins is 14.

Step-by-step explanation:

To minimize the count of bills and coins, start with the largest denominations that fit within the amount.

The change due is $39.49.

Start with:

-$20 bill (largest under $39.49)

Remaining: $19.49

-$10 bill (largest under $19.49)

Remaining: $9.49

-$5 bill (largest under $9.49)

Remaining: $4.49

Then:

4 × $1 bills (to cover $4.49)

Remaining: $0.49

-$0.25 coin (quarter)

Remaining: $0.24

2 × $0.10 coins (dimes)

Remaining: $0.04

4 × $0.01 coins (pennies)

The final composition includes:

1 twenty-dollar bill

1 ten-dollar bill

1 five-dollar bill

4 one-dollar bills

1 quarter

2 dimes

4 pennies

Totaling 14 pieces.

Answer:

The top surface area of the washer equals 160.14 square millimeters.

Step-by-step Explanation:

The washer's top surface forms an annulus, characterized by an outer radius of 10 mm and an inner radius of 7 mm (obtained since the hole's diameter is 14 mm and the radius is half the diameter).

Recall the formula for the area of an annulus:

where R is the outer radius and r the inner radius.

Substituting the given values:

Thus, the calculation yields: