Hello,
Please, see the attached file.
Thanks.
0.30 is the same as 3/10 so then you would add 3/10 and 4/10 which equals 7/10 which then gives you with 3/10 ice cream left
The slope is -5. Find two lattice points (points with integer coordinates) and find (y1-y2)/(x1-x2) with the two points being (x1,y1) and (x2,y2). The equation would be

, or -5.