The ratio of an object's weight on earth to its weight on neptune is 5 : 7. how much would a person who weighs 150 pounds on earth weigh on neptune? a. 107 1/7 pounds b. 750 pounds c. 170 pounds d. 210 pounds

5:7
In english, what this is saying is that for every 5 units of weight on Earth, is 7 units of weight on Neptune. 
Given this, it would make sense that your weight on Neptune, say Y, equals your weight on Earth, say X, divided by five, then multiplied by seven.
Y = (X/5) * 7
Y = (150/5) * 7 = 210