2X+23= 91 2X=91-23 2X=68 X=34
327-3X=15+48 327-15-48=3X 264=3X X=264÷3=88
15+X+2+21=47 X=47-15-2-21 X=8
32+2X-5=77 2X=77-32+5 2X=40 X=20
X=638-542+117 X=213
19+X<43 X<43-19 X<24 X∈ { 0,1,2,3,4,5,......23}
28-X≥11 28-11≥X X≤17 X∈ {0,1,2,3,........17}
X+38-18<83 X< 83-38 +18 X< 63 X∈ {0,1,2,3,......62}