Richard B. answered 07/04/25
Experienced Math Tutor for Grades 5 - 9; Patient and Results-Oriented
How do you set up and solve a word problem like “twice a number plus 5 is 17”?
First of all this is a two part question. First you are asking how to set up the problem. This is done by translating English into an Algebraic Equation (meaning there is at least one unknown, i.e., or variable, in the equation). Then lastly, you are asking how to solve the Algebraic Equation? This is done by performing inverse operations to both sides of the Algebraic Equation.
The part of the question above that needs to translate from English into an Algebraic Equation is:
“twice a number plus 5 is 17“. Then to solve the Algebraic Equation you need to calculate what the number is that makes this statement true by using the appropriate inverse mathematical operations.
To translate, “twice a number plus 5 is 17“ into an algebraic equation, use the following rules, which are not necessarily collectively exhaustive:
“+” : plus, more than, the sum of, the total of, add, increased by;
”-“ : minus, less than, decreased, the difference of;
”x” : times, product, twice (2 times), multiplied by;
”/“ : quotient, divided, ratio; and
“=“ : is, equals
Using these rules, I can start translating the above phrase, into mathematical operations. So “Twice” is translated into mathematics as 2 times. “A number” is the unknown that makes this equation an Algebraic Equation. We use English letters in algebra to represent an unknown value. These letters are most often, x, y, z, a, b, c, m, or n. I’ll choose the most popular of theee Algebraic letters, “x”. “Plus” means to +. “Is” means =.
So combining the phrase and the rules above I get the following Algebraic Equation:
2x + 5 = 17. This is the answer to the first part of the question, how do you set up a word problem.
Now to solve an algebraic equation with one variable, I need to use reverse operations to get all the constant values on one side of the equation and the unknown (variable) alone on the other side of the equation. Then after combining the constants, that value becomes the value for the unknown, and the word problem is solved.
So to solve this Algebraic Equation, 2x + 5 = 17,
first perform the reverse operation of +5, which is -5, to both sides of the equation. Five is subtracted from both sides of the equation in order to keep the equation balanced. This gives: 2x + 5 - 5 = 17 - 5.
Combining the constants to simplify the equation, we get 2x = 12. Now 2 is also a constant and it is connected to the unknown x by multiplication. The inverse of multiplication is division. So now divide both sides of the equation by 2. We get:
2x/ 2 = 12/2
Then simplifying we get X = 6. Now that completes the second part of the question of how to solve the word problem.
We can check this answer by substituting 6 for the unknown (or variable “x”) in the original equation to see if we get the answer 17. If so, we would have done this step correctly.
2(6) + 5 =17
12 + 5 = 17
17 = 17
Problem solved correctly.