Multiples of 15 are: 15,30,45,60,75,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315,330,345,360,375,390,405,420,435,450,465,480,495,510,525,540,555,570,585,600,615,630,645,660,675,690,705,720,735,
the second answer is correct if they messed up on the question and meant to ask for the MAD of set B
I think the 3rd answer is incorrect (I got 1.09), so you might want to double-check your 3rd answer since it is asking for "times bigger", not how much bigger, which means how many times larger is the MAD of set A than that of set B and to find how many times bigger a number is than another number, you have to divide the first number by the second number.
The lateral area is the side area of the pyramid. In this case, there are 3 sides because the base is a triangle. Since the base is an equilateral triangle, all sides are of equal dimensions. So, the sides of the pyramid are also all of the same size, area.
We then just have to figure out the area of one of the side triangles, then multiply it by 3 to get the total lateral area of that pyramid.
We know how to calculate the area of a triangle: A = (b * h)/2