Ответ:

1) c⁶/6y⁴–c/12y³=2c⁶–cy/12y⁴

2) m+3/5m³n+2n²–3/10mn=2m+6+2m²n²–3m²/10m³n

3) 3x+2/5x–5x+3y/10xy – y–1/2y=6xy+4y–5x+3y–5xy–5x/10xy=xy+7y–10x/10xy