А) 3/7 + 4/9 = 55/63
б) 17/18 - 11/12 = 1/36
в) 7/9+4/15 = 1 2/45
г) 1/8+4/9 = 41/72
д) 8/9-7/8 = 1/72
е) 7/16+1/6 = 29/48
ж) 9/14+37-1/28 = 37 9/14 - 1/28 =37 19/28
з) 9/11-2/5 = 23/55
и) 13/15-2/3 = 1/5
к) 5/6+2/9 = 1 1/18
л) 1/6+1/4-1/8 = 5/12 - 1/8 = 7/24
м) 13/16+9/32 = 1 3/32
н) 20/21+4/7 = 1 11/21
о) 10/21+9/14 = 1 5/42
п) 1/3-1/6+1/4 = 1/6 + 1/4 = 5/12
р) 3/28+5/14.= 13/28