34-[45-78]=

To solve the expression \( 34 - [45 - 78] \), you first need to calculate the expression inside the brackets:

1. Calculate \( 45 - 78 \): \[ 45 - 78 = -33 \]

2. Now substitute \(-33\) back into the expression: \[ 34 - (-33) \]

3. Simplifying the equation gives: \[ 34 + 33 = 67 \]

So, the result of \( 34 - [45 - 78] \) is \( 67 \).