If you place a 21-foot ladder against the top of a building and the bottom of the ladder is 12 feet from the bottom of the building, how tall is the building? Round to the
nearest tenth of a foot.

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

hope it