Answer:
Andre's equation: y=5x+100
Elena's equation: y=20x+10
Explanation:
total money (y) = (amount per week) times number of weeks (x) + (starting amount)
to solve number 3, plug in 4 for x in both equations and solve for y.
then find the difference between the two values.
to solve number 4, because both equaions are already set equal to y, you can set them equal to each other so you have 5x+100=20x+10
then solve for x to find number of weeks and plug this value into one of the equations for y to find how much money they have in their bank account.