Question 973719
-7-20-(-14)

-27 is the first two terms.  -7 minus 20 is minus 27.  
-27 -( -14)  is now adding (two minus signs).  -27+14= - 13

Two minus signs make a plus.  I agree with that.
Subtraction is a minus sign.  The last two decades, people have been adding a negative, which has confused a lot of people.  You can't change a minus sign to a plus sign without multiplying by minus 1.  When there is a minus sign, leave it and subtract.  When you have two minus signs together, THEN you add.