to change the temperature from -13 on Saturday to -4 on Sunday, you would need to add 9 degrees ( -13 + 9 = -4 )
so you need the equation that would also = 9
-4 + 13 = 9
-4 - (-13) = 9
-4 -13 = -17
4 +(-13)= -9
there are 2 equations that equal the correct change in temperature, but since both temperatures are negative ( -13 & -4)
the correct equation would also contain 2 negative numbers
so correct equation should be: -4-(-13) =
