Let the cost of the trumpet be represented as \( x \).
According to the information given, the cost of the guitar is 4 times the cost of the trumpet. Therefore, we can write the equation:
\[ 4x = 380 \]
To find the cost of the trumpet, you can solve for \( x \) by dividing both sides of the equation by 4:
\[ x = \frac{380}{4} \]
\[ x = 95 \]
So, the cost of the trumpet is $95.