The maximum level of lead allowed in drinking water is 15 μg/kg. What is this concentration in units of parts per million? show work

Growing crops in places where major pests don't live using beneficial insects to eat harmful insects using a rat trap instead of a rodenticide developing drought-resistant tomato plants using beneficial insects or natural oils to repel pests planting a different crop every year to fake out the pests keeping food covered to deter ants and rodents developing bean plants with a resistance to fungus picking caterpillars off tomato plants cultivation practice biological control cultural control genetic resistance natural chemicals