Answer:52
Step-by-step explanation:
Given
one-fifth of the plants in a garden are grape tomato plant
two-ninth of the plants in the garden are cherry tomato plants
Also there are 18 grape tomato and 20 cherry tomato plants.
Let Total plants be x
Then Grape tomato plants 
x=90
thus there are total of 90 plants
also grape tomato+cherry tomato=18+20=38
Thus there are 90-38=52 remaining plants.
If you add them together you will get 11g
Well percents are probability, and probability is similar to theory. So i think its theoritical probability.
Hope this helps.
You have to put the problem down we cant help you if its not there
sorry but please put equation in or problem