A factory has two assembly lines M and N that make the same toy. On Monday only assembly line M was functioning and it made 900 toys. On Tuesday both assembly lines were functioning for the same amount of time. Line M made 300 toys per hour and line N made 480 toys per hour. Line N made as many toys on Tuesday as line M did over both days. Write an equation that can be used to find the number of hours t that the assembly lines were functioning on Tuesday.