A (X+25)x3-100=17
3X+75-100=17
3X=17+100-75
3X=42
X=14
B (X+19)x3+11=103x2
3X+57=206-11
3X=206-11-57
3X=138
X=46
C (440:4-100)+X/3=21
(110-100)+X/3=21
10+X/3=21
X/3=21-10
X/3=11
X=33
D ( X/5+6)x8-190=186
( X/5+6)x8=186+190
(x/5+6)x8=376
X/5+6=376:8
X/5=47-6
X/5=41
X=205