Answer:
=19
Step-by-step explanation:
Answer:

Step-by-step explanation:

lowest common multiple of 2 and 3 is 6
21×3 = 63
21×2= 42
they are now going to have the same denominator of 6

now u are just gonna add the neumerators and keep the denominator

Im not sure but I think its Option I
Answer:
The sun released a strong burst of water vapor. As Earth cooled, water in the atmosphere condensed. Materials collided due to strong gravitational forces. The ozone layer formed to protect against harmful UV ray exposure
Step-by-step explanation: