856. Найдите число x, для которого верно равенство: а) x + 1/8 = 3/5; б) 1/3 + x = 5/12; в) x − 3/20 = 1/5; г) x − 3/7 = 4/21; д) 4/5 − x = 1/6; е) 5/8 − x = 1/3.

1. \(x=\dfrac35-\dfrac18=\dfrac{24}{40}-\dfrac5{40}=\dfrac{19}{40}\).
2. \(x=\dfrac5{12}-\dfrac13=\dfrac5{12}-\dfrac4{12}=\dfrac1{12}\).
3. \(x=\dfrac15+\dfrac3{20}=\dfrac4{20}+\dfrac3{20}=\dfrac7{20}\).
4. \(x=\dfrac4{21}+\dfrac37=\dfrac4{21}+\dfrac9{21}=\dfrac{13}{21}\).
5. \(x=\dfrac45-\dfrac16=\dfrac{24}{30}-\dfrac5{30}=\dfrac{19}{30}\).
6. \(x=\dfrac58-\dfrac13=\dfrac{15}{24}-\dfrac8{24}=\dfrac7{24}\).

Ответ: а) \(\dfrac{19}{40}\); б) \(\dfrac1{12}\); в) \(\dfrac7{20}\); г) \(\dfrac{13}{21}\); д) \(\dfrac{19}{30}\); е) \(\dfrac7{24}\).