9. Two marks exercise problem III

\(A\) has '\(a\)' rows and '\(a + 3\)' columns. \(B\) has '\(b\)' rows and '\(17 - b\)' columns, and if both products \(AB\) and \(BA\) exist, find \(a\), \(b\)?

 

\(a\) \(=\)

 

\(b\) \(=\)