\(2/5a+6 \begin{bmatrix} 3&\\ -2& \\7& \end{bmatrix} = \begin{bmatrix} 15& \\ -10 & \\35 \end{bmatrix}\)
we realize that the each element in the matrix was multiplied by 5 so a must be a value that will make 2/5a+6= 5 therefore a must be a negative reciprocal of 2/5 thus we will get -5/2 because that gives us -1 and when you add -1+6=5 which satisifes the equation.
hope this helped. :)
\(2/5a+6 \begin{bmatrix} 3&\\ -2& \\7& \end{bmatrix} = \begin{bmatrix} 15& \\ -10 & \\35 \end{bmatrix}\)
we realize that the each element in the matrix was multiplied by 5 so a must be a value that will make 2/5a+6= 5 therefore a must be a negative reciprocal of 2/5 thus we will get -5/2 because that gives us -1 and when you add -1+6=5 which satisifes the equation.
hope this helped. :)