Important information
12 lawns can be mowed in 3 hours
We need to know how many they can mow in 18 hours
Solving the question
Knowing that 12 lawns can be mowed in 3 hours we will take that and find the unit rate, we do this by dividing the numbers by each other.
lawns÷hours= how many hours per lawn
12÷3 = 4 ← Meaning they can mow 1 lawn in 4 hours
Finding the unit rate is helpful because if you want from here you can just add it 18 times.
Now we are going to multiply 18 by our unit rate of 4 to find our answer
18×4 = 72
Meaning in 18 hours they can mow 72 lawns
Statement
Therefore in 18 hours they are able to mow 72 lawns