What is the relationship between the magic constant (the sum of each row) and the sum of all the numbers in the square? Why does this relationship make sense?

Let's say each row sums to 15

If we had 3 rows, then the total sum would be 3*15 = 45

If we added all of the values in the 3x3 magic square, then we'd get 45 as well.

This is one example showing that

sum of all values = (number of rows)*(magic constant)

You can replace "rows" with columns to get the same idea, because each column also adds to the same magic constant. The diagonals are an exception since we only have two of them.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

answer: 94

step-by-step explanation: 79+91+92+94+94 = 450 divided by 5 (since there are 5 number that are being added) = 90