Answer:
1,100
Explanation:
15*10*2=300
20*15*2=600
20*10=200
300+600+200=1,100
you need to find the surface area which means the area of all the sides except the top(bc i think its open???)
a shortcut i used was multiplying sides that have the same area by 2. for example, the side 15*10, there was another side like that, so i multiplied by two instead of having to solve for the other side individually, does that make sense?
check my math if im wrong