a light bulb is a kind of tool for seeing in the dark & as the time a tool lasts increases , the number of tools discarded will decrease ->  as the time a lightbulb lasts increases, the number of lightbulbs discarded will decrease  to dispose of something can mean to discard something & humans move waste to a landfill for disposal / storage ->  humans discard waste in a landfill  humans discard waste in a landfill & landfills have a negative impact on the environment ->  humans discarding waste in a landfill has a negative impact on the environment  humans discarding waste in a landfill has a negative impact on the environment & a light bulb is a kind of tool for seeing in the dark0 ->  humans discarding objects in a landfill has a negative impact on the environment  humans discarding objects in a landfill has a negative impact on the environment & decreasing something negative has a positive impact on a thing ->  decreasing the number of objects discarded in landfills by humans has a positive impact on the environment  decreasing the number of objects discarded in landfills by humans has a positive impact on the environment & a light bulb is a kind of object ->  decreasing the number of light bulbs discarded in landfills by humans has a positive impact on the environment  as the time a lightbulb lasts increases, the number of lightbulbs discarded will decrease & decreasing the number of light bulbs discarded in landfills by humans has a positive impact on the environment ->  increasing the time that a lightbulb lasts has a positive impact on the environment by decreasing the number of light bulbs discarded in landfills  if an object is discarded in a landfill then that object is trash & a light bulb is a kind of object ->  if a light bulb is discarded in a landfill then that lightbulb is trash  increasing the time that a lightbulb lasts has a positive impact on the environment by decreasing the number of light bulbs discarded in landfills & if a light bulb is discarded in a landfill then that lightbulb is trash ->  increasing the time that a lightbulb lasts has a positive impact on the environment by decreasing the amount of trash discarded in landfills  increasing the time that a lightbulb lasts has a positive impact on the environment by decreasing the amount of trash discarded in landfills & something that has a positive impact on something else is a kind of benefit -> a benefit of increasing the time that a lightbulb lasts is  decrease in the amount of trash discarded in landfills