Equal units

When a problem is about a ratio, the bar is cut into equal units. A ratio of 3 to 2 means three units of one thing for every two of another.

Once you know what one unit is worth, every other amount follows. Find the unit first; everything else is multiplying.

A cook who uses flour and sugar in the ratio 3 : 2 draws three equal boxes for flour and two for sugar. If the flour is 450 g, three boxes are 450 g, so one box is 150 g.