45+45=90
(35+35)+20=90
(25+25)+(20+20)=90
20•4+10=90
<span>13 15 18 19, 31 35 38 39, 51 53 58 59, 81 83 85 89, 91 93 95 98.И того 20 )</span>
<span>(а+3,3-а)-(3,3+х)=</span><span>а+3,3-а-3,3-х= -х</span>
14 9/16 - х = 6 3/4 + 1 2/5
14 9/16 -х = 7 + (15/20 + 8/20) = 7 + 1 3/20 = 8 3/20
14 9/16 - х = 8 3/20
х = 14 9/16 - 8 3/20 = 6 + (9/16 - 3/20) = 6 + 45/80 - 12/80 = 6 33/80
х = 6 33/80