Which of the following are true statements about a variable? Select all that apply. * 3 points A.) The number in front of a letter in an expression. B.) A symbol used to represent an unknown value. C.) Can be changed from one value to another. D.) Always has to be the letter x.

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years

Acentral angle measuring 160 degrees intercepts an arc in a circle whose radius is 4. what is the length of the arc the circle formed by this central angle? round the length of the arc to the nearest hundredth of a unit. a) 4.19 units b) 6.28 units c) 12.57 units d) 12.57 square units

There are 85 apples on the big tree, john picked out 15%. how many did john pick out?