(1)4,20,12最小公倍数是60；(2)x-(3分之1-4分之1）=8分之5x-(4/12-3/12)=5/8x-(1/12)=5/8x=5/8+1/12x=15/24+2/24x=17/24(3)4分之1+2x=4分之17 2x=17/4-1/4 2x=16/4 2x=4 x=4÷2...