Question

Help me it's algebra and dont tell me to look at the lesson :)

Answer 1

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.)