to find the highest temperature, we must look at the most positive number. in this list, all of the positive temperatures are; 7F, 4F, 1F and 3F. out of this list, 7 is the highest temperature.
now, find the lowest temperature. we do the same method as before, but now look for the most negative number. out of -2 and -5, -5F is the lowest temperature
find the difference: 7 - -5
remember that subtracting a negative is equivalent to changing the sign to positive
7 + 5 = 12.
the difference is 12 degrees F.