5,5 : (2,62 + 1,78)

To solve the expression \( 5.5 : (2.62 + 1.78) \), we first need to evaluate the expression inside the parentheses:

1. Calculate \( 2.62 + 1.78 \): \[ 2.62 + 1.78 = 4.40 \]

2. Now, divide \( 5.5 \) by the result: \[ 5.5 : 4.40 = \frac{5.5}{4.40} \]

3. To simplify the division: \[ \frac{5.5}{4.40} = 1.25 \]

So, \( 5.5 : (2.62 + 1.78) = 1.25 \).