math VERY URGENT
posted by Anonymous on .
Mrs. Black has one begonia plant. If she buys two begonia plants each year for every one she has, how many will she have in four years?
Please explain the answer.

every year she has 3 times as many plants
1+3+9+27+81 = 121 
first year 1
second year 2+1
third year 6 +2+1
fourth year=18+6+2+1
total= sum above 
24 plants
first year 1+2=3
second year 3x2=6
third year 6x2=12
fourth year 12x2=24 
First year
1+ 2=3
Second year
3+2+2+2=9
Third year 9+2+2+2+2+2+2+2+2+2=27
Fourth year
27+[27•2]=81