Atemperature is -4 f. a high pressure front increase the temperature to 8 f. by how many degrees did the temperature increase

The temperature increases by a total of 12 degrees.  

Step-by-step explanation:

A good way to solve a problem with positive and negative integers is to plot them on a number line and find the difference from one point to the next.  On a number line, positive numbers go to the right of zero and negative numbers go to the left of zero.  If we start at a temperature of -4 and count to the right on the number line until we get to +8, there will be a difference of 12.  The other way to set up the problem is to subtract the numbers,  8-(-4)=12.  

System A: The lines overlap.

System B: The lines never intersect.

System C: The lines intersect at a point not on the y-axis.

System D: The lines intersect at the y-intercept.

Step-by-step explanation:

Got them right.