The reason for this is because they both share two pairs of angles that are the same: 40 degrees and 60 degrees. If these are equal, then that must mean the third angle for both triangles is also the same, making both triangles equal in proportion. Therefore, they must be similar.
Think about before the 12 campers got off the bus. So, in addition to 27 campers that stayed inside the bus (12+27), it would equal 39 campers in total.
Given that the associative property of multiplication says that you can group the numbers in any combination, we can reorganize the expression as: 7·(10·3)=210. So the answer would be the first option.
