The difference between 2.4 and a number is 1.61, as shown below. What number should go in the box to complete the subtraction problem? 2.4 minus 0.box 9 equals 1.61

On a piece of paper graph f(x)=5•(0.4)^x

Find the unit rate for: 75% high-fiber chimp food to 25% high -protein chimp food.

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.