Question

Difficulty: EasySolving Linear Equations

For a certain value of xx, the expression 25x+3\frac{2}{5}x + 3 is equal to 1111. What is the value of 2x+52x + 5?

  1. A
    11.4
  2. B
    21
  3. C
    27
  4. 45Answer
  5. E
    85

Answer

45
To find the value of 2x+52x + 5, we first isolate the variable xx in the equation 25x+3=11\frac{2}{5}x + 3 = 11. Subtracting 33 from both sides gives 25x=8\frac{2}{5}x = 8. Multiplying both sides by the reciprocal of the coefficient, 52\frac{5}{2}, yields x=8×52=20x = 8 \times \frac{5}{2} = 20. Finally, substituting x=20x = 20 into the expression 2x+52x + 5 gives 2(20)+5=40+5=452(20) + 5 = 40 + 5 = 45.

Step-by-Step Solution

1
Set up the equation based on the text and subtract 3 from both sides of the equation to isolate the variable term.
25x=8\frac{2}{5}x = 8
To solve for xx, we first need to isolate the term containing xx.
2
Multiply both sides of the equation by 52\frac{5}{2} to solve for xx.
x=20x = 20
Multiplying by the reciprocal of the coefficient cancels the fraction, leaving xx isolated.
3
Substitute x=20x = 20 into the expression 2x+52x + 5.
2(20)+5=452(20) + 5 = 45
The question asks for the value of 2x+52x + 5, so we evaluate it using the solved value of xx.

Key Concept

Solving Linear Equations

Alternative Method

We can also multiply the entire equation by 55 first to eliminate the fraction: 2x+15=552x + 15 = 55. Subtracting 1515 from both sides gives 2x=402x = 40. Since the target expression is 2x+52x + 5, we can simply add 55 to both sides of 2x=402x = 40 to get 2x+5=452x + 5 = 45, avoiding the need to solve for xx directly.
Estimated Time:45s
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