Jawaban:

Let's use algebra to solve the problem. Let's call the cost of the raincoat "r" (in dollars).

According to the problem, we know that the umbrella costs 5 dollars more than the raincoat. So, the cost of the umbrella can be expressed as "r + 5" (in dollars).

We also know that the total cost of the raincoat and umbrella is 5 dollars and 40 cents, which can be expressed as 5.40 dollars.

Putting it all together, we can write an equation:

r + (r + 5) = 5.40

Simplifying the equation:

2r + 5 = 5.40

Subtracting 5 from both sides:

2r = 0.40

Dividing both sides by 2:

r = 0.20

Therefore, the raincoat costs 0.20 dollars, or 20 cents.