The sum of 7-1 and 7-2 will be a rational number because sum of rational numbers is a rational numbers.
A rational number is a number which can be written in p/q form where q≠0.
We know that when two rational numbers is added then the sum is also a rational number. And when two rational numbers are subtracted then the difference is also a rational number.
So in the given question, lets study the term differently that is,
i) 7 - 1 is a rational number because their difference is equal to 6 and it can be written in p/q form which is 6/1.
ii) 7 – 2 is also a rational number as their difference will be 5 which is a rational and can be written in p/q form which is 5/1.
So when these two rational numbers are added their sum will also be a rational number which is 11.
Learn more about rational numbers here : brainly.com/question/12088221
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Answer:
Step-by-step explanation:

They are the opposite of each other. Like if one function has the point (1,3) the inverse function with have the point (3,1)
If you multiply $60 by 0.15 you'll get 9 which is the taxes of the meal. Since he leaves the same percentage of tip, now we add 9+9 and get $18..
60+18=78