Question

a grid (2x2) with numbers: first row 12, 15; second row 8, and a blank cell. task is to find the missing number.

Explanation:

Step1: Find the ratio of the first row

The first row has 12 and 15. The ratio of 12 to 15 is $\frac{12}{15}=\frac{4}{5}$.

Step2: Apply the ratio to the second row

The second row has 8. Let the unknown number be $x$. We have $\frac{8}{x}=\frac{4}{5}$. Cross - multiplying gives $4x = 8\times5$. Then $4x=40$, and $x = \frac{40}{4}=10$.

Answer:

10