Question

aratati ca 1a1-1a+8 divide 9

Answer 1

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1a1 - 1a + 8 = 1*100+10*a+1 - (10*1+a) + 8 =
                  =  100+1-10+8 +10a-a = 99+9a = 9*(11+a) $\vdots\;9$

Answer 2

1a1-1a+8 divide 9
a×110+10×a+8
a×120+8
a×128 divide 9

a=128:9
a=31 rest 1
1a1-1a+8 nu divide 9