To solve the proportion
\[ \frac{15}{2} = \frac{y}{75} \]
you can cross-multiply. This means multiplying the numerator of the first fraction by the denominator of the second fraction, and the numerator of the second fraction by the denominator of the first fraction:
\[ 15 \times 75 = 2 \times y \]
Calculating the left side:
\[ 15 \times 75 = 1125 \]
Now you have:
\[ 1125 = 2y \]
Next, solve for \(y\) by dividing both sides by 2:
\[ y = \frac{1125}{2} = 562.5 \]
Thus, the solution is
\[ y = 562.5 \]