X - y = 4

2x + y = -4

x = y =

 x = 4 + y

                x= -2 - y/2

Step-by-step explanation:add y to both sides of the equation

constant acceleration- a

constant velocity- c

no velocity or acceleration- b

explanation:

for body moving with a constant acceleration, the rate of change of displacement changes over time. this is proven by the increasing gradient of the curve (a) against time.

a body that is moving at constant velocity covers equal distances over equal periods of time, thus the straight line with a constant gradient c.

a stationary body   covers no displacement as time elapses. thus the flat line with   zero gradient.

the correct answer is the second option