An inequality can be formed by simply translating the problem statement to numerical expressions.
From the problem we know that

added with

hours should be equal or greater than

(helpful insight from the keyword "at least"). Therefore, it's inequality would look like:

(>= is used instead of ≥ for constraints in formatting)
The inequality above best models the situation.
Y=2x^3 is nonlinear, since it's a cube equation. y=x+5 is linear, because it's a line with y intercept (0,-5) and slope 1. y=\sqrt(x-5) is nonlinear, because it's a quadratic equation when reversing x and y. 5x+5y=25 is equal to x+y=5 ot y=-x+5, which is also linear. y=x^2/2 is a quadratic equation, so it's nonlinear.
For the first image can you give us the choices for each one?
Sam has 50 paper clips
If one paper clip has a length of 1/10 foot than 10 paper clips would make 1 foot.