I dont even know how to explain this, but please help

Both Px + Qy = R and Tx + Uy = V have the same solution (2, 9), meaning the point (2, 9) lies on both lines such that x = 2 and y = 9 makes both equations true.

When you add these equations together, you get

(Px + Qy) + (Tx + Uy) = R + V

→   (P + T ) x + (Q + U ) y = R + V

so the first option is equivalent.

When you subtract the first equation from the second, you get

(Tx + Uy) - (Px + Qy) = V - R

→   (T - P) x + (U - Q) y = V - R

so the third option is also equivalent.

y=3x+4

step-by-step explanation:

given the points a(0,4) and b(-4, -8)

eqn of line ab: (y-4)/(x-0)=(-8-4)/(-4-0)

(y-4)/x=-12/-4=3

y=3x+4