Can you help me answer the questions please

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Find the unit rate. enter your answer as a mixed number. a fertilizer covers 2/3 square foot in 1/2 hour.

An is a number that is written without a component. it is a number that is either or . an exponent is a or a number that another number is being to. the number that is being raised to a is called the . the or power tells you how many times to the base by . if an exponent is fractional then ask yourself the question: what when multiplied by itself a certain number of times will equal the number?