Simplify each expression using order of operations.
4. 24 + (8-5)
5. 4 + 7 X2
6. 9-9 + 22
7.8 x 3 + 6-1
8. 3 + 12 - 2
9. 4+ (3 X 6) - 3

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)