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

Prove that 3: 8 is equivalent to 12: 32.a. use diagrams to support your answer.

45 was divided by a power of ten to get 4.5. what power of ten was it divided by? people 4.5

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a