Please help I have been stuck on these homework question for a long time!!

a)

What will happen as the following two pulses interfere? Each square on the grid represents 1 unit.The resulting pulse will have an amplitude of 1 unit. The pulses will continue moving afterward. The resulting pulse will have an amplitude of 3 units and this resulting pulse will continue to move to the left. The resulting pulse will have an amplitude of 3 units. The pulses will continue moving afterward. The resulting pulse will have an amplitude of 1.5 units. The pulses will continue moving afterward.A wave has a speed of 1520 m/s and a frequency of 4.20 Hz. What is its wavelength