Answer:
you have to convert them to equivalent units (the same denominators)
Step-by-step explanation:
first, multiply 2 and 7 by 4.
now you have 8/21.
then, make the other fraction the same value.
multiply 1 and 4 by 7.
7/21.
now your equation is 7/21 + 8/21= 15/21.
