Question

What is sum and the difference of two rationales 5/7 and 4/3 are the results also rationals

Answer 1

Given rationals,
5/7 and 4/3

Sum of the two rationals:-
=5/7+4/3
LCM is 21
=5/7×3/3+4/3×7/7
=15/21+28/21
=(15+28)/21
=43/21

Difference of the two rationals:-
=5/7-4/3
LCM is 21
=5/7×3/3-4/3×7/7
=15/21-28/21
=(15-28)/21
=-13/21

Yes,the results are also rational numbers.

Hope it helps

Answer 2

4/3-5/7

LCM=21

4*7/3*7-5*3/7*3

28/21-15/21

(28-15)/21

13/21

The difference of two rationals is a rational number.
4/3+5/7
4*7/3*7+5*3/7*3
28+15/21 =43/21 The sum of rational numbers is also a rational number