All you have to do is add like terms,
3.2x +(-5.6x)= -2.4x
-6+4= -2
Anyway, answer is
-2.4x-2
Y=mx+b, and you are told that b=2.5 so
y=mx+2.5, now using point (4.5,-4.25) we can solve for m
-4.25=4.5m+2.5
-6.75=4.5m
-1.5=m so now we have the line:
y=-1.5x+2.5
#2 is slope 1/3 and t intercept of 6 if I’m not mistaken