Find 0.2B
B=[50 10
25 15]

Multiplying a matrix by a scalar results in every entry in a matrix get multiplied by that scalar, as defined,
[tex]a\begin{bmatrix}b&c\\d&e\\\end{bmatrix}=\begin{bmatrix}ab&ac\\ad&ae\\\end{bmatrix}[/tex]
So in our case, ([tex]0.2=\frac{1}{5}[/tex]
[tex]\frac{1}{5}\begin{bmatrix}50&10\\25&15\\\end{bmatrix}=\begin{bmatrix}\frac{50}{5}&\frac{10}{5}\\\frac{25}{5}&\frac{15}{5}\\\end{bmatrix}=\boxed{\begin{bmatrix}10&2\\5&3\\\end{bmatrix}}[/tex]
Hope this helps :)