Let's start by defining the variable \( b \) as the number of balloons that Alexa popped.
According to the problem, Krista popped 6 balloons, which is 1 balloon less than the number of balloons popped by Alexa. Therefore, we can express this relationship using the following equation:
\[ b = 6 + 1 \]
This simplifies to:
\[ b = 7 \]
So, Alexa popped 7 balloons.