To solve for the value of \( b \), we start from the equations you provided:
- \( s = 4b \)
- \( s + b = 55 \)
Now, substitute the expression for \( s \) from the first equation into the second equation:
\[ 4b + b = 55 \]
Now, combine like terms:
\[ 5b = 55 \]
Next, solve for \( b \) by dividing both sides by 5:
\[ b = \frac{55}{5} = 11 \]
Thus, the value of \( b \) is \( 11 \).
To find the value of \( s \), substitute back into the first equation:
\[ s = 4b = 4 \times 11 = 44 \]
So, Michael used 44 strawberries and 11 bananas in his smoothie batch.