853. Выполните вычитание и проверьте сложением: а) 5/12 − 1/3; б) 1/5 − 3/20; в) 7/8 − 5/12; г) 9/10 − 1/6.

1. \(\dfrac5{12}-\dfrac13=\dfrac5{12}-\dfrac4{12}=\dfrac1{12}\). Проверка: \(\dfrac1{12}+\dfrac13=\dfrac1{12}+\dfrac4{12}=\dfrac5{12}\).
2. \(\dfrac15-\dfrac3{20}=\dfrac4{20}-\dfrac3{20}=\dfrac1{20}\). Проверка: \(\dfrac1{20}+\dfrac3{20}=\dfrac15\).
3. \(\dfrac78-\dfrac5{12}=\dfrac{21}{24}-\dfrac{10}{24}=\dfrac{11}{24}\). Проверка: \(\dfrac{11}{24}+\dfrac5{12}=\dfrac{11}{24}+\dfrac{10}{24}=\dfrac78\).
4. \(\dfrac9{10}-\dfrac16=\dfrac{27}{30}-\dfrac5{30}=\dfrac{22}{30}=\dfrac{11}{15}\). Проверка: \(\dfrac{11}{15}+\dfrac16=\dfrac{22}{30}+\dfrac5{30}=\dfrac9{10}\).

Ответ: а) \(\dfrac1{12}\); б) \(\dfrac1{20}\); в) \(\dfrac{11}{24}\); г) \(\dfrac{11}{15}\).