She can get 21 portions. Since 2/3 and 42/3 already share the same denominator, all you need to do is divide 42 by 2 to get 21.
Here is a graph. When you use a graphing calculator, it isn't always necessary to solve for y.
Note different colors are used for the different problems. Problem 2 has a dashed line, as described by "Remember, ...".
9*13=117
12*16=192
We increased three meters to both the length and width of the garden.