a.)

$144.00 / 76 lbs = $1.895 / lb

The price of 1 pound of mercury is $1.895.

1 lbs = 453.592 gr

76 lbs = 76 x 453.592 = 34473 g

$144.00 / 34473 g = $0.0042 / g

The price of 1 gram of mercury is $0.0042

1 cm^3 of mercury is equivalent to 13.534 g (click mercury conversion for more details)

13.534 g x $0.0042 / g = $0.057 / cm^3

The price of 1 cubic centimeter of mercury is $0.057.

1 cubic centimeter of mercury  = 0.061 in^3 (click mercury conversion for more details)

1 cubic inch of mercury = 1/0.061 = 16.393 cm^3

$0.057 / cm^3 x 16.387 cm^3 = $0.934 / cubic inch

1 cubic inch of mercury costs $0.934.

b.)

2.650 cubic inches x $0.934 / cubic inch = $2.475

The price of the mercury used to make one manometer is $2.475.

15 manometers x $2.475 / manometer = $36.765

The price of the mercury used to make 15 manometers is $36.765.