You can
put this solution on YOUR website! .
Writing such system is easy, standard and routine task
x + y = 280 liters (1) (total volume)
0.25x + 0.20y = 61 liters (2) (amount of "real fruit juice")
In this system, x is the volume of the 25% juice (drink A), and
y is the volume of the 20% juice (drink B).
Your request is satisfied: the requested system of equations is written.