Solve for x :

Find three numbers given: a) The second number is the twice of the first. b) The third number is three times the first number. c) Their sum is 180.

Rose keeps quarters, nickels and dimes in her change jar. She has a total of 52 coins. She has three more quarters than dimes. She has five less nickels than dimes. How many dimes does she have?

Using only 32-cent and 20-cent stamps, Catherine put $3.36 postage on a package she sent to her sister. She used twice as many 32-cent stamps as 20-cent stamps. Determine how many of each type of stamp she used.