\(A=9+a+a+....+a\)
\(=9+99a\)
\(=9+99\times2\)
\(=9+198\)
\(=207\)
\(B=140\times3-\left(a+a+a+....+a\right)\)
\(=420-40a\)
\(=420-40\times3\)
\(=420-120\)
\(=300\)
A= 9 + a + a + a +...+ a (99 sô a) B = 140 x 3 - (a + a + a +.....+a) (40 sô a)
A= 9 + 99 x 2 Vì a = 2 B = 420 - 40 x3
A= 9 + 198 B = 420-120
A= 207 B =300