Answer:
a. 4.5 grams per cup
b. 3.2 ounces per week
c. 19.2 grams per cubic centimeters
d. $3.29 per gallon
Explanation:
The unit rate is simply a ratio comparing 2 given quantities, whereby the denominator is 1.
The unit rate of the above given problems can be determined as shown below:
a. 18 grams of salt per 4 cups, to find the unit rate, calculate how many grams of salt you'd get in 1 cup by dividing 18 by 4

Unit rate = 4.5 grams per cup
b. 19.2 ounces is gained by the baby in 6 weeks.
Unit rate is the amount of ounces gained in 1 week
Unit rate =

Unit rate = 3.2 ounces per week
c. Unit rate =

Unit rate = 19.2 grams per cubic centimeters
d. Unit rate =

Unit rate = $3.29 per gallon