In Exercises 1 and 2, write the verbal sentence as an equation.

The sum of 3 and z is 10.

A symbol we usually pick letters to be symbols, usually represents a number. Any letter you choose can be a variable.

A variable is a symbol that stands in for an unknown value in a mathematical expression. A variable expression is a combination of terms and mathematical operations that contains at least one variable. Example a + 2x + 10

An equation is a mathematical statement that two expressions are equal. The solution of an equation is the value that when substituted for the variable makes the equation a true statement.

Example: 3x + 5 = 14 is an equation, in which 3x+5 and 14 are two expressions separated by an ‘’equal’’ sign.

Converting the phrase into an equation:

In the left side, the phrase is ''the sum of 3 and z''. Sum means the addition and z is the variable and the right side is 10.

Now we can write ‘’ the sum of 3 and z’’ is

$3+z$

The equation is $3+z=10$