The interest rate on deposits in a certain bank initially equaled \( 5\% \) per year but then it was decreased by \( 20\% \). By how many percentage points has the interest rate decreased?
The interest rate on deposits in a certain bank initially equaled \( 5\% \) per year but then it was increased by \( 1.2 \) percentage point. What was the percentage increase of the interest rate?
Find the real number \( a \) such that the following system of equations has no solution.
\[ \begin{aligned} \frac25x-\frac a4y&=4 \\ -\frac x4 + \frac{5y}8&=\frac52 \end{aligned}\]