Question 1081114
The water in the pond is the initial amount at T=0, plus the rate * time:

    W = 500 + 35T

    where: W = number of liters in pond
                 T = time in minutes,  {{{ T >= 0 }}}

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{{{ drawing(400,400, -100, 900, -1000, 9000,
            line(0,500, 242.85, 9000),
             grid(1))
        }}}