50+51+52++101=can you me? i do not understand

Suppose

At the same time, we can write

Note that (just reverse the sum). Let's pair the first terms of and , and the second, and the third, and so on:

Now, each grouped term in the sum on the right side adds to 151. There are 52 grouped terms on that same side (because there are 50 numbers in the range of integers 51-100, plus 50 and 101), which menas

But , as we pointed out, so

4 adults and 12 babies

step-by-step explanation:

4 x 7 = 28

12 x 15 = 180

180 + 28 =208

4 x 3 = 12