Problem Statement:
A cook can cook 4 large cakes in an hour.
A cook can cook 12 small cakes in an hour.
A kitchen is available for two hours for cooks to use.
How many cooks will it take to cook 29 large cakes and 220 small cakes in the kitchen?
Let X = the number of cooks it takes to cook 29 large cakes and 220 small cakes in 2 hours.
This can be considered as two separate problems added together:
L = number of cooks to cook 29 large cakes in 2 hours.
S = number of cooks to cook 220 small cakes in 2 hours.
X = L + S
Part 1:
How many cooks will it take to cook 29 large cakes in 2 hours?
Let L = number of cooks to cook 29 large cakes in 2 hours.
A cook can cook 4 large cakes in an hour.
Let rate l = 4 (units = large cakes cooked/cook*hour)
Write an equation for this part of the problem:
29 = L * 2 * l
Look at the units on both sides of the = sign. They should be the same.
29 (large cakes cooked) = L (cooks) * 2 (hours) * l (large cakes cooked/cook*hour)
Solve for L:
Replace l with 4
29 = L * 2 * 4
Divide both sides of the = sign by 2 * 4 = 8 and switch the left and right sides of the = sign.
L = 29/8 > 3
L = 4 cooks
Part 2:
How many cooks will it take to cook 220 small cakes in 2 hours?
Let S = number of cooks to cook 29 large cakes in 2 hours.
A cook can cook 12 small cakes in an hour.
Let rate s = 12 (units = small cakes cooked/cook*hour)
Write an equation for this part of the problem:
220 = S * 2 * s
Look at the units on both sides of the = sign
220 (small cakes cooked) = S (cooks)* 2 (hours) * s (small cakes cooked/cook*hour)
Replace s with 12
220 = S * 2 * 12
Divide both sides of the = sign by 2 *12 = 24 and switch the left and right sides of the = sign.
S = 220/24 > 9
S = 10 cooks
Solve for X
X = L + S = 4 + 10
X = 14 cooks