So 45,000 mL per horse every day. that is the same as 45 Liters per horse every day. Then there's four horses, so that's 180 Liters total every day. So then in five days:
Each horse drinks 45,000 mL of water each day. Since there are 4 horses, the total of water will be 4*45000mL = 180000 mL per day In five days, the four horses consume 5*180000mL = 900000mL
