Помогите срочно: ( 1 - 3/4 ) * ( 4/5 - 3/4 ), ( 1/2 + 1/3 + 1/4 ), 1/3 * 6/7 - 1/7 * 3/4

(1-3/4)*(4/5-3/4)=1/801)4/4-3/4=1/42)4/5-3/4=16/20-15/20=1/203)1/4*1/20=1/80(1/2+1/3+1/4)=6/12+4/12+3/12=13/12=1 1/121/3*6/7-1/7*3/4=2/7-3/28=8/28-3/28=5/28