Answer:
Explanation:
There are many ways this could be done, but the simplest way is to divide 18 into 72. That gives 4. So each plot is 4 * 20 = 80 m^2
If you are willing to use fractions, the answer could be 20*72 / 18 = 8 * 10 which is more feasible and still gives 80, but the land may not permit it. However math will.
It's hard to give an exact answer when it is this open ended.