48+56=104; 170-104= 66. The librarian needs to pack 66 more books.
Let b be the number of blue beads and g the number of green beads that Giovanni can use for a belt.
He's supposed to use a total of between 70 and 74 beads, so
70 ≤ b + g ≤ 74
The ratio of green beads to blue beads is g/b, and this ratio has to be between 1.4 and 1.6, so
1.4 ≤ g/b ≤ 1.6
For completeness, Giovanni must use at least one of either bead color, so it sort of goes without saying that this system must also include the conditions
b ≥ 0
g ≥ 0
(These conditions "go without saying" because they are implied by the others. g/b is a positive number, so either both b and g are positive, or they're both negative. But they must both be positive, because otherwise b + g would be negative. I would argue for including them, though.)
Answer:
5, 8, 11, 14, 17,....
f(n) = 5+3n where n is the number of steps after the first two. 7 steps is 20 faces.
Step-by-step explanation:
A sequence is a list of numbers that are related. The first number in the sequence is 5 since the first part of the stairs has 5 faces (5 squares, the dark don't count). Every time you add a "stair" you add 2 blocks - one underneath to support and one as the step. This adds 3 faces. So 5 becomes 8. Repeat and 8 becomes 11. You add 3 faces each time. So the sequence is
5, 8, 11, 14, 17,....
This is a constant pattern of adding 3 each time after the initial start. So we can write a rule. We start with 5 + 3(each stair step). So if the cube is 7 stairs high, that is 5 more repetitions of adding blocks after the start (remember the start has 2 steps already). So 5 + 3(5) = 20. 7 steps high will have 20 faces.
