The length of the orange umbrella is 40% of the length of the blue umbrella.

The length of the orange umbrella is 40% of the length of the blue umbrella. Find the length of the blue umbrella if the orange umbrella is 36 cm long.

To solve this problem, we introduce the conditional variable “X”, through which we denote the length of the blue umbrella.

Then, based on the data of the problem, we will compose the following proportion: 40% relate to 36 centimeters in the same way as 100% relate to X centimeters.

Then, based on this proportion, we will compose the following equation: X x 40 = 36 x 100.

Solving this equation, we get X = (36 x 100) / 40 or X = 9 x 10 or X = 90 centimeters.

Answer: The length of the blue umbrella is 90 centimeters.