I believe it is 4/12 since you have a total of 12 marbles and only 4 are red plastic ones
I just did it on paper but hope that helps:)
Maximizing the Area of a rectangle. Drag the locators to vary the width of the rectangle and see the effect on its area. For a rectangle with a perimeter of 40, the height is always 20 minus the width. This allows you to reduce the formula for the area. I hope this helps you
The equation would be a-44=64÷4
Sarah's age is 60