When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide.
Hey There! :)
I have this same question on an assignment I have to do and I was trying to figure it out as well and was gonna see if anybody else had this question answered. I'm sorry, I wish I could help. I'll get back to you if I have help and get it done. Good luck!