The cost of the flour is x * $3 = $3x.
The cost of the eggs is 3 * $10 = $30.
The cost of the milk is 7 * $5 = $35.
The cost of the baking soda is 2 * $3 = $6.
The total cost for everything is the sum of the costs of the flour, eggs, milk, and baking soda: $3x + $30 + $35 + $6.
We are given that the total cost is $80, so we can write: $3x + $30 + $35 + $6 = $80.
Simplifying the left side, we get: $3x + $71 = $80.
Subtracting $71 from both sides, we get: $3x = $9.
Dividing both sides by $3, we get: x = 3.
The value of x is 3.
#### 3
The answer is: 3
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
A baker bought cooking ingredients in the supermarket. She bought x boxes of flour that cost $3 each box, 3 trays of eggs that cost $10 for each tray, 7 liters of milk that cost $5 each liter, and 2 boxes of baking soda that cost $3 each box. How much will she have to pay for everything?
If we know the answer to the above question is 80, what is the value of unknown variable x?

### Answer:
