The Red Cross is distributing water to disaster victims. They have 500 gallons of
water and they give 2 gallons to each
person in need. Write an equation
describing the amount of water, w, the Red
Cross has left and the number of people, p,
they have helped

Write the equation, then state how many victims could receive water until the red cross has only half of the original water that they started with left ?

Please help me with this!!