А) 2/9+3/7= 14/63+27/63= 41/63
б) 7/8+3/4= 7/8+6/8= 13/8= 1ц5/8
в) 5/24+25/36= 15/72+50/72= 65/72
г) 59/60+39/40= 118/120+117/120= 235/120= 1ц115/120= 1ц23/24
д) 3ц1/8+2ц1/7= (3+2)+(7/56+16/56)= 5+23/56= 5ц23/56
е) 5ц1/6+1ц2/3= (5+1)+(1/6+2/3)= 6+(1/6+4/6)= 6+5/6= 6ц5/6