You find the variable x or y in one of the lines of the problem and then substitute the value of the variable you first found into the other line of the problem to find the other variable. Then, you plug all of the values you found into either line/equation of the problem to ensure that one side of the equation you pick is equal to what is on the other side of the "=" symbol.
What are the values to choose from?
Answer:
Step-by-step explanation:
A. If children are considered people under the age of 18, then the answer would be
13 < a < 18 where the a represents age, where the inequality signs do not have an equals to because those ages are excluded
B. This inequality can be shown on a number line with open circles denoting the endpoints 13 and 18 as they are not included, and a line connecting these two points which represents the ages encompassed by the range
A is the right option! Because 0.40 should be in second equation with the x to represent the number of stamps multiply by 40 cents.