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Example

Solving a Two-Number Problem Using "Sum" and "More Than Twice"

Apply the seven-step problem-solving strategy to a number problem that combines multiplication and addition in the relationship between two unknowns, producing a three-step equation.

Problem: One number is ten more than twice another. Their sum is one. Find the numbers.

  1. Read the problem.
  2. Identify what to find: two numbers.
  3. Name the unknowns using a single variable. Let xx = the first number. Because one number is "ten more than twice" the other, the phrase combines two operations: twice signals multiplication by 22, and ten more than signals adding 1010. The second number is therefore 2x+102x + 10.
  4. Translate into an equation: Their sum is 11, so:

x+(2x+10)=1x + (2x + 10) = 1

  1. Solve the equation. First, combine like terms x+2x=3xx + 2x = 3x:

3x+10=13x + 10 = 1

Subtract 1010 from both sides:

3x=93x = -9

Divide both sides by 33:

x=3x = -3

Find the second number: 2(3)+10=6+10=42(-3) + 10 = -6 + 10 = 4.

  1. Check: Is 44 ten more than twice 3-3?

2(3)+10=?42(-3) + 10 \stackrel{?}{=} 4

6+10=?4-6 + 10 \stackrel{?}{=} 4

4=44 = 4 \checkmark

Is their sum 11?

3+4=?1-3 + 4 \stackrel{?}{=} 1

1=11 = 1 \checkmark

  1. Answer: The numbers are 3-3 and 44.

This example extends earlier two-number problems in two ways. First, the relationship between the unknowns involves two operations — multiplication followed by addition — rather than a simple additive phrase like "five more than." The expression 2x+102x + 10 captures both operations in a single algebraic expression. Second, the resulting equation 3x+10=13x + 10 = 1 requires three algebraic steps (combining like terms, subtracting, and dividing) rather than two, because combining xx and 2x2x into 3x3x is needed before the inverse operations can isolate the variable.

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Updated 2026-04-21

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