What does simplify the expression mean in math?

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year the population of her town is changing by a constant rate

An angle that measures between 90 and 180° is called a(,

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days