Answer: Barbara did not include a variable in the term , which must represents the number of bottles of iced tea she needs to sell.
Step-by-step explanation:
Let be "x" the number of bottle of water Barbara needs to sell and "y" the number of bottle of iced tea she needs to sell.
She sells iced tea for $1.49 per bottle and water for $1.25 per bottle, so she can write the following equation in order to calculate the number of bottles she needs to sell to earn $100:
Since Barbara wrote this equation:
We can conclude that the error Barbara made in writing the equation was: She did not include a variable in the term , which must represents the number of bottles of iced tea she needs to sell.