a) \( 3,4x = 4,08 \)
\( x = 4,08 : 3,4 \)
\( x = \frac{408}{100} : \frac{34}{10} = \frac{408}{100} \cdot \frac{10}{34} = \frac{408}{340} = \frac{12}{10} = 1,2 \)
б) \( 8,24a = 824 \)
\( a = 824 : 8,24 \)
\( a = \frac{824}{1} : \frac{824}{100} = 824 \cdot \frac{100}{824} = 100 \)
в) \( 34,6 + c = 346 \)
\( c = 346 - 34,6 \)
\( c = 311,4 \)
Ответ: \( x = 1,2 \); \( a = 100 \); \( c = 311,4 \).