Solve each question. round to the nearest tenth if necessary. 7r – 7 = 2r + 18

Suppose i flip two identical coins. what is the probability that i get one head and one tail?

Acoin bank containing only dimes and quarters has 12 more dimes than quarters. the total value of the coins is $11. how many quarters and dimes are in the coin bank?

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?