Final answer:
The two possible dimensions of a rectangle with a perimeter of 90 cm are 25 cm x 20 cm and 30 cm x 15 cm.
Step-by-step explanation:
To find the dimensions of a rectangle with a perimeter of 90 cm, we need to consider the formulas for perimeter and area of a rectangle. The perimeter of a rectangle is given by the formula P = 2l + 2w, where l is the length and w is the width. Since we know that the perimeter is 90 cm, we can set up the equation 2l + 2w = 90. We can then solve for the dimensions by trial and error or by plugging in the given options. Out of the four options provided, option a) 25 cm x 20 cm and option b) 30 cm x 15 cm satisfy the equation, so they are the two possible dimensions of the rectangle with a perimeter of 90 cm.