<human>:  The moon is made of 50% iron, 20% carbon, and the remainder is other elements. Mars weighs twice as much as the moon, but has the exact same composition. If Mars is 150 tons of other elements, how many tons does the moon weigh?
<bot>: How much of Mars is made up of other elements? ** 30% of Mars is made up of other elements because 100 - 50 - 20 = <<100-50-20=30>>30
How much does Mars weigh? ** Mars weighs 500 tons because 150 / .3 = <<150/.3=500>>500
How much does the moon weigh? ** The moon weighs 250 tons because 500 / 2 = <<500/2=250>>250
#### 250