I need help!! Exponential equations

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years

Rhombus adef is inscribed into a triangle abc so that they share angle a and the vertex e lies on the side bc . what is the length of the side of the rhombus if ab=c, and ac=b.

Solve this system of equations: y=x2-3x + 12 y=-2x+14 4. substitute the values of x, -1 and 2, into either origina equation to solve for the values of y. what are the solutions of the system of equations?