Answer:
23 chickens
Explanation:
Step 1: Set Up a System of Equations
We know that this farmer has some unknown amount of chickens, and some unknown amount of cows. Let's assign a letter to each unknown variable - let the number of chickens be c, and the number of cows be w.
The problem tells us that the farmer has a total of 30 animals (cows and chickens together). Therefore, c + w = 30.
We are then given some information about how many legs the animals have. Recall that a chicken has 2 legs and a cow has 4. Since (we are assuming that) each animal has the "normal" number of legs, we can represent the number of chicken legs as 2c and the number of cow legs as 4w. Since the animals have 74 legs in all, we know that 2c + 4w = 74.
Step 2: Solve the System
We now have the following system of equations:
c + w = 30 (1)
2c + 4w = 74 (2)
The problem is asking us to find the number of chickens, or c. Note that this means we do not have to find the number of cows, or w, so let's manipulate the system to eliminate w, which will make solving for c easier. Solving, we get:
4c + 4w = 120 (3) (Multiply (1) by 4)
2c = 46 (Subtract (2) from (3))
c = 23 (Divide by 2)
Thus, the farmer has 23 chickens.