Find the sum without the use of a number line.
21/38 + (-7/19) note: 21/38 and -7/19 are fractions

If you multiply both sides of fraction any number except 0, you end up with the same number. In order to make easy adding fractions first equalise their denominators. 38=2*19. So we need to multiply both sides of (-7/19) fraction by 2. We get (-14/38). As denominators are the same we can "connect" the fractions. (21-14)/38=7/38.

the square root of 16 is 4.

4*4 = 16