Answer:
Let's start by using variables to represent the number of rows containing 20 vines and 25 vines. Let:
x be the number of rows containing 20 vines
3x be the number of rows containing 25 vines (since there are 3 times as many rows containing 25 vines as there are rows containing 20 vines)
We know that Sarah plants a total of 760 vines, and that each row contains either 20 vines or 25 vines. Therefore, we can write an equation based on the total number of vines:
20x + 25(3x) = 760
Simplifying and solving for x:
20x + 75x = 760
95x = 760
x = 8
So there are 8 rows containing 20 vines, and 3 times as many rows containing 25 vines, or 3(8) = 24 rows containing 25 vines.
Therefore, Sarah planted 8 rows with 20 vines and 24 rows with 25 vines.