Shreya places 10 gemstones in a line. The first is 2 cm from point X, the second is 4 cm from the first, the third is 6 cm from the second, and so on. How far is the tenth gemstone from X?
Cynthia creates a three-digit passcode and wants exactly two of its digits to be 6. How many passcodes can she create? A passcode may begin with 0. Examples include 663 and 066.
Orange soda is sold in boxes of 9 cans for \$7. One free can is given for every 2 boxes bought, and 5 empty cans can be exchanged for one free can. What is the greatest number of cans obtainable with \$35?