PLS HELP IVE BEEN ASKING FOR 4 HOURS NOT A SINGLE PERSON HAS BEEN RIGHT ITS PAST DUE :( JUST TROLLS I WILL GIVE BRAINLIEST JUST PLS HELP

Answer:
Answer is in attachment. I am really sorry if I'm wrong.
Step-by-step explanation:
Greatest common factor (GCF) is the highest number that is a factor of 2 numbers. Not sure if that makes sense.
For example, GCF of 8 and 4 is 4, because 4 is the highest factor that fits into both numbers. 4x2=8 and 4x1=4.
In this case, the height is 7, because that's the GCF of 21 and 70. There's no bigger common factor than that. 7x3=21 and 7x10=70
Now that we know the "height", even though there's no such thing as height when calculating the area, we know the length.
The area of something is length x width. Your assignment calls it height for some reason so we'll use height x length.
Area of the 2 shapes is already given, which is 21n for the first shape. Length of the first shape is 3n because 3nx7=21n. Recall that 7 is what we found earlier.
As we can see, the "height" of the 2nd shape is the same as the first, therefore it should also be 7.
Since we are given the area of the 2nd shape, we now know its length. Length of 2nd shape is 10, because 7x10=70.