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

To solve the expression \( 5.5 : (2.62 + 1.78) \), follow these steps:

1. First, calculate the sum inside the parentheses: \[ 2.62 + 1.78 = 4.4 \]

2. Next, divide \( 5.5 \) by \( 4.4 \): \[ 5.5 : 4.4 = \frac{5.5}{4.4} \]

3. To simplify \( \frac{5.5}{4.4} \), you can convert to decimals or fractions. Here: \[ \frac{5.5}{4.4} = \frac{55}{44} = \frac{55 \div 11}{44 \div 11} = \frac{5}{4} = 1.25 \]

Therefore, the answer is: \[ 5.5 : (2.62 + 1.78) = 1.25 \]