Explanation:
The easiest way to do this is to make use of the 2-point form of the equation for a line. For points (x₁, y₁) and (x₂, y₂), the equation is ...

Filling in your given points, the equation becomes ...

After you fill in the values, it is a matter of simplifying the resulting equation.

Current Weight Weight after adding Marbles
Giulio: 2x 2x + 10
Jim: x x + 5
You didn't post the options so hopefully you can determine the answer based on the info I provided above.
27 because half of 18 would be 1/3 of your muffins, 1/3 of the muffins is 9 and add that third to the 2/3 and you're back to your original amount.
It would take 6 hours. Because if you're going 240 miles "per hour", just multiply 240 by 6 and you get 1440.