(68)5/6-1/6
(69)2/5+1/2
(70)3/4+1/6
(71)2x-2/5=27/5
(72)4x=12×4
(73)6.5+2x=16.5
(74)8.1÷27×3
(75)1-2/5-17/50
(76)4/7-2/5
(77)8³
(78)5/6-1/4+2/3
(79)11/28+(5/14+3/7)
(80)7-(3/4-2/5)
(81)x+1/3=7/9
(82)2x-1/6=5/6
(83)3/5-x=1/4
(84)x-4/5x-1.6=1.5
(85)14.6-(4.6+7.2)
(86)1-1/2-1/3-1/6
(87)3/10-7/30+4/10