40 casting is made of copper and zinc. \( 65 \% \) of the casting is copper and there are 147 g of zinc. What is the mass of the casting?

To find the mass of the casting, we know that 65% of it is copper, which implies that 35% is zinc. Since we have 147 g of zinc representing 35% of the total mass, we can set up an equation. Let the total mass of the casting be \( x \). We can express this as: \[ 0.35x = 147 \] To find \( x \), we divide both sides by 0.35: \[ x = \frac{147}{0.35} \] \[ x = 420 \text{ g} \] So, the mass of the casting is 420 grams. And there you have it—easy peasy!