Answer:
rational numbers are numbers that can be written as the ratio of two integers
Answer: Approximately 1.9 atm
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Work Shown:

If the volume is 3.5 liters, then the pressure is approximately 1.9 atm.
Note the increase in volume leads to the reduction of pressure, and vice versa. The two variables have an inverse relationship.
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As a check,

We don't get the exact thing on both sides, but the two sides are close enough. We have rounding error due to P2 being not exact.
A more accurate check could be

which has the two sides much closer to one another. This helps us verify the answer.
Answer:
Therefore,
.......Equation
Angelica's Brother's age is 11 years old.
Step-by-step explanation:
Given:
Let the current age of Angelica's Brother be 'x' years old
Angelica's current age is 13 years old,
According to given condition,
Therefore the Equation will be,

On solving this equation we get

Therefore,
Angelica's Brother's age is 11 years old.
Therefore,
.......Equation
Angelica's Brother's age is 11 years old.
the answer for x is 33 I hope this is right