For each pair of numbers, tell: by what percent of the first number is the second number larger? by what percent of the second number is the first number smaller? 10 and 15

Imagine a new pasture with grass growing on it. every day after the seeds have germinated, the number of blades of grass in the pasture triples. after 18 days, the entire pasture is completely covered in grass. how many days did it take for the pasture to be one-third covered in grass?

Find three consecutive numbers such that the sum of one-fourth the first and one-fifth the second is five less than one-seventh the third

What is the missing step in this proof ?