12) Calculate: \( 5 y^{2}+4 x \), when \( x=2.5 \) and \( y=3 \) \( 3 \times 3 \times 1 \)

To calculate \(5y^2 + 4x\) with \(x = 2.5\) and \(y = 3\), first substitute the values into the equation. You get \(5(3^2) + 4(2.5)\). Calculating \(3^2\) gives \(9\), then \(5 \times 9 = 45\). For \(4(2.5)\), that results in \(10\). Finally, \(45 + 10 = 55\). So, the result is \(55\). Now, onto \(3 \times 3 \times 1\): This is straightforward! Multiplying \(3 \times 3\) gives \(9\), and then \(9 \times 1\) keeps it at \(9\). So, there you have it: \(5y^2 + 4x = 55\) and \(3 \times 3 \times 1 = 9\).