Solve for N

We use the Solve for N technique to determine the value of an unknown number in a proportion. When two shapes have the same ratio, we can express the both fractions as equal to each other. As in a rectangle, the long side A of the small rectangle divided by the short side B of the small rectangle will equal the the long side C of the larger rectangle divided by the short side D of the larger rectangle. The cross product of the the two similar shapes will equal each other as shown below.

To continue with the example, the small rectangle is 3 divided by 2 and the larger rectangle is N divided by 4. We cross multiply N times 2 which equals 3 times 4. We divide by 2 on both sides to get the N by itself, so N equals 3 times 4 and then we divide the answer by 2 to get 6.

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