HELP PLEASE simplify (4^3)^5

Aresearch group wants to find the opinions’ of city residents on the construction of a new downtown parking garage. what is the population of the survey downtown shoppers downtown visitors downtown workers city residents

1) you deposit $2,500 in an account that earns 4% simple interest. how much do you earn in eight years?

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