6,4+y/2=8,5

Let's solve the equation step by step:

Given: \[ 6.4 + \frac{y}{2} = 8.5 \]

1. Subtract 6.4 from both sides: \[ \frac{y}{2} = 8.5 - 6.4 \] \[ \frac{y}{2} = 2.1 \]

2. Multiply both sides by 2 to solve for \( y \): \[ y = 2.1 \times 2 \] \[ y = 4.2 \]

Answer: \( y = 4.2 \)