3.5+-7.5= -4 how do you ge this answer?

Question

How do I come up with answer -4.

Answer 1

Lets say you have two numbers having a tug-a-war.  3.5 and -7.5

 

 

The negative number is winning by some number of points because it has a higher number than the positive number.  To find out how much the negative number is winning over the positive number, we subtract the two numbers as if the signs were positive.

 

7.5 - 3.5 = 4

 

The negative number is winning by 4.  We keep the negative sign because it overpowers the positive sign.  Your final result is -4.

Answer 2

Say that I owe you $7.50 (that's the -7.5)

I pay you $3.50 (that's the 3.4)

I still owe you $4.00 (that's the -4)

 

OK