A9543B represents a six-digit number in which A and B are digits different from each other. The number is divisible by 11 and also by 8. What digit does A represent?

The tower shown has no gaps. Suppose it is painted red on all exterior sides including the bottom, and then cut into cubes along the indicated lines. How many cubes will each have red paint on just three faces?

The “staircase” shown is 4 units tall and contains 10 unit squares. Suppose the staircase were extended until it was 12 units tall. How many unit squares would it then contain all together?

Triangle ABC has its vertices A, B, C on the sides of a rectangle 4 units by 5 units as shown. What is the area of the triangle ABC in square units?

Using the letters A and B, the following two-letter code words can be formed: AA, AB, BB, BA. Using the letters A, B, and C, how many different three-letter code words can be formed?

In a stationery store, pencils have one price and pens have another price. Two pencils and three pens cost 78¢. But three pencils and two pens cost 72¢. How much does one pencil cost?