Номер 3,4номер не надо делать
(1/8+2/9-1/4)*5 1/7:(7/9-2/3+1/6)=1 4/5 1) 1/8+2/9-1/4=9/72+16/72-18/72=7/72 2) 7/72 * 5 1/7=7/72 * 36/7=1/2 3) 7/9 - 2/3+1/6=28/36 - 24/36+6/36=10/36=5/18 4) 1/8 : 5/18=1/2*18/5=9/5=1 4/5