1) (86+х+90):3 = 80,
176+х=240, х=240-176=64.
2) (58,2+49,4+х):3=54,3.
107,6+х=162,9, х=162,9-107,6=55,3.
3) (2⅔+1¾+3¹/¹²):3 = (2⁸/¹²+1⁹/¹²+3¹/¹²):3 = 6¹⁸/¹²:3 = 7⁶/¹²:3 = 7½:3 = ¹⁵/²×¹/³ = 5/2 = 2,5 или 2½.
