(45 - 18 ) + х = 79
27 + х = 79
х = 79 - 27
х = 52
__________
(45 - 18) + 52 = 79
(7) 14 21 28 35 42 49 56 63 70 77 84 91 98
(17) 17 34 51 68 85
(23) 23 46 69 92
2 3/4+(-2/5+1 1/2)-(3/4-5/6)+3 1/6=11/4:(-2/5+3/2)-(19/12):19/6=11/4:11/10+19/12*6/19=11/4*10/11+1/2=1/2*5+1/2=5/2+1/2=3