Calculation:

The product of the numerator of the ratio and of the denominator of the other is known as a cross product. Cross products can be used to determine whether the ratios form a proportion or not. If the cross products are equal, then the ratios form a proportion.

\(\displaystyle{\frac{{{60}}}{{{15}}}}={\frac{{{12}}}{{{y}}}}\) [Write the proportion.]

\(\displaystyle{60}\times{y}={15}\times{12}\) [Apply cross products property.]

\(\displaystyle{60}{y}={180}\) [Multiply.]

\(\displaystyle{\frac{{{60}{y}}}{{{60}}}}={\frac{{{180}}}{{{60}}}}\) [Divide each side by 24 to place the variable on one side of the equation]

\(\displaystyle{y}={3}\) [Simplify.]

Hence, the solution of the proportions \(\displaystyle{\frac{{{60}}}{{{15}}}}={\frac{{{12}}}{{{y}}}}\) is \(\displaystyle{y}={3}\).

The product of the numerator of the ratio and of the denominator of the other is known as a cross product. Cross products can be used to determine whether the ratios form a proportion or not. If the cross products are equal, then the ratios form a proportion.

\(\displaystyle{\frac{{{60}}}{{{15}}}}={\frac{{{12}}}{{{y}}}}\) [Write the proportion.]

\(\displaystyle{60}\times{y}={15}\times{12}\) [Apply cross products property.]

\(\displaystyle{60}{y}={180}\) [Multiply.]

\(\displaystyle{\frac{{{60}{y}}}{{{60}}}}={\frac{{{180}}}{{{60}}}}\) [Divide each side by 24 to place the variable on one side of the equation]

\(\displaystyle{y}={3}\) [Simplify.]

Hence, the solution of the proportions \(\displaystyle{\frac{{{60}}}{{{15}}}}={\frac{{{12}}}{{{y}}}}\) is \(\displaystyle{y}={3}\).