Hey, can you help me?

The unit rate is $0.22 lb

Explanation:

The given parameters are;

The price for 18 lb = $3.99

We have;

The unit rate is the price for one unit. Whereby the unit of measurement is the lb, we have that one unit = 1 lb.

Therefore, given that 1 lb = 18 lb/18, the price of 1 lb which is the unit rate is given as follows;

18 lb price = $3.99

Divide both sides by 18 to get;

18 lb/18 =  $3.99/18 = $0.221

Therefore, we have;

1 lb = 18 lb/18 = $0.221

The unit rate, which is the cost for 1 lb to the nearest hundredth = $0.22/lb.

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask