The ratio between containers A and B equals to the ratio of heights of the containers. Find the volume of container A when the height of the container A is 0,5 m and the volume of the container B is 3000 liters and the height is 0,75 m.

3 is greater then both of those numbers

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graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.