How many atoms of h are in 2.8 mol n2h4?

Since perimeter means all around it just means adding all the sides. Because you are given length and width your equation would then be, " (5)+(5)+(2x=14)+(2x+14). Now since area means length times width you would multiply length times width. Since x=7 you would multiply 7x5 and the area equals 35. Questions 35-37 are indeed correct. You're smart ! By the way I'm twelve so hopefully you found this helpful.