Which number stays the same when adding or subtracting fractions with unlike denominators?

The empire state building in new york city is 1454 feet tall a model of a building is 24 inches tall what is the ratio of the height of the model to the height of the actual empire state building

Solve the x in the equation x^2+14x+17=-96

The marriott family bought a new apartment three years ago for $65,000. the apartment is now worth $86,515. assuming a steady rate of growth, what was the yearly rate of appreciation? what is the percent of the yearly rate of appreciation?