Tìm x biết x+7,78=42,8

a) \(x + 7,78 = 42,8\)

               \(x = 42,8 - 7,78\)

               \(x = 35,05\).

Vậy \(x = 35,05\)

\(x - 5,767 = 200 - 13,2\)

\(x - 5,767 = 186,8\)

            \(x = 186,8 + 5,767\)

            \(x = 192,567\).

Vậy \(x = 192,567\).

c) \(34,8:x = 7,2 + 2,8\)

    \(34,8:x = 10\)

              \(x = 34,8:10\)

              \(x = 3,48\).

Vậy \(x = 3,48\).