8.
a) 15a =153
b) 2a9= 279
c) 333a= 3330,3339
d)12ab0 =12420,12240,12330,12510,12150
9.
a)44x | 10<=>x=0
b)88x | 3<=>(8+8+x)|3=>((16+x)|3=>x=2;5;8
c)29x | 5<=>x=0;5
d)65xx | 2<=>x=0;2;4;6;8
e)30x | 9<=>(3+0+x)|9<=>(3+x)|9<=>x=3
f)407x | 3<=>(4+7+x)|3<=>(11+x)|3<=>x=4;7
g)100 | 780x<=>x=0
h)45x2 | 9<=>(4+5+x+2)|9<=>(11+x)|9<=>x=7
