200 + 10a + b = ((10a+b) * 7) -4
200 + 10a + b = (70a+7b) -4
204 = 60a+6b
34 = 10a+b
a = 3
b = 4
ba = 43
200+10a+b=7(10a+b)-4
10b+a=?
204=7(10a+b)-(10a+b)
204=6(10a+b)
$\frac{204}{6}=10a+b$
34=10a+b
(ab)=34
(ba)=43 bulunur.