Question

To determine the value of one variable when the value of other is given

Answer 1

Answer:

Evaluating an Expression with one Variable. A mathematical expression can have a variable as part of the expression. If x=3, the expression 7x + 4 becomes 7 * 3 + 4 which is equal to 21 + 4 or 25. To evaluate an expression with a variable, simply substitute the value of the variable into the expression and simplify.

Answer 2

Explanation:

Let us understand the problem with an example.

An equation with two variables is given by

x + y = 0

Now assume x is given. Let x = 5

We have to find the value of y.

So put x = 5 in the above equation.

Then y = - 5

Note: It is understandable that when the value of one variable in an equation is given, to find the value of the other variable, we simply substitute the given value.