Landons front lawn measures 20 feet by 8 feet he counts to find that there are 120 blades of grass per square inch how many blade do grass are in the entire lawn use proportions

First step is to convert feet into inches:
1 foot = 12 inches
20feet = 20*12=240 inches
8feet = 8*12=96 inches

Now we can calculate total area:
A = height * width
A= 240 * 96
A=23040 inches²

We know the amount per one inch² and we need to find out total number of blades:

1 inch²                          120 blades
23040 inches²               x blades

Now we cross-multiply numbers:
1*x = 23040 * 120
x= 2764800

There are total of 2764800 blades in the entire lawn