Answer:
add all the sides together
a+b+c+d
<span>Look at the definition of multiplicative inverse. If two numbers are multiplicative inverses of each other, then by definition, their product will be equal to 1. And 1 is a positive number. If both numbers being multiplied are positive, then the result is positive. And of both numbers being multiplied are negative, then the result is still positive. But if one number is positive and the other is negative, then the result is negative. So if you want a positive result, then both numbers you're multiplying have to have the same sign. And since we want a result of 1 for multiplicative inverses and since 1 is positive, then the numbers being multiplied have to have the same sign.</span>
Are you trying to find the area?
Answer:
12 students
Step-by-step explanation:
Given

Required
Determine the number of students that eat lunch once a week
In Sets;
If out of 9, at least 7 eats one a week then
9 - 7 eats lunch once a week

<em>In other words;</em>
2 out of 9 students eat lunch once a week
Number of students in this category is then calculated as thus;




I'm pretty sure its the second one