Answer:
d. 40 pounds
Step-by-step explanation:
We know both weights of the astronaut, and we know one of the weight of the rock... we need to find the other weight of the rock (on Earth).
The easiest way to deal with those problems is to use a cross-multiplication.
We'll place on top the weights on Earth and as denominators the weights on Mars:
[tex]\frac{x}{16} = \frac{180}{72}[/tex]
So we isolate x = (16 * 180) / 72 = 2,880 / 72 = 40 pounds.
The rock then weights 40 pounds on Earth.
