To solve this problem, we need to determine the value of x, which represents the number of bigger panda bears.
Let's break down the information given:
Number of small panda bears: 4
Number of bigger panda bears: x
Amount of fresh bamboo sprouts eaten by small panda bears per day: 25 pounds
Amount of fresh bamboo sprouts eaten by bigger panda bears per day: 40 pounds
Total amount of fresh bamboo sprouts eaten per day: 25 pounds * 4 small panda bears + 40 pounds * x bigger panda bears
Total amount of fresh bamboo sprouts eaten per week: 7 days * (25 pounds * 4 small panda bears + 40 pounds * x bigger panda bears)
Total amount of fresh bamboo sprouts eaten per week: 2100 pounds
We can set up the equation as follows:
7 * (25 * 4 + 40 * x) = 2100
Let's simplify and solve for x:
7 * (100 + 40x) = 2100
700 + 280x = 2100
To isolate x, we subtract 700 from both sides of the equation:
700 + 280x - 700 = 2100 - 700
280x = 1400
To solve for x, we divide both sides of the equation by 280:
x = 1400 / 280
x = 5
The value of x is 5.
#### 5
The answer is: 5
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
Four small panda bears and x bigger panda bears eat 25 pounds and 40 pounds of fresh bamboo sprouts every day, respectively. The 9 pandas eat 2100 pounds of bamboo in a week. What is the value of unknown variable x?

### Answer:
