Answer:
b=320; slope=-30
Explanation:
if you look along the y-axis find the spot that the line intercepts and then that's b
now for the slope
find two points on the line, i chose(8 , 120) and (4 , 240)
use the slope formula: y2-y1 over x2-x1
240-120=120 and 4-8= -4
so the slope is 120/-4 and that can be simplified to 30/-1 or -30