A casting is made of copper and zinc. 65% of the casting is zinc and there are 147g of copper. We need to find the total mass of the casting.

1. Problem Description

A casting is made of copper and zinc. 65% of the casting is zinc and there are 147g of copper. We need to find the total mass of the casting.

2. Solution Steps

Let $M$ be the total mass of the casting.

The percentage of zinc is 65%, so the percentage of copper is $100\% - 65\% = 35\%$.

The mass of copper is 147g, which represents 35% of the total mass. We can write this as:

$0.35M = 147$

To find the total mass $M$, we divide both sides of the equation by 0.35:

$M = \frac{147}{0.35}$

$M = \frac{14700}{35}$

$M = \frac{2940}{7}$

$M = 420$

3. Final Answer

The mass of the casting is 420g.

The answer is B. 420g.