In a fraction, the numerator and denominator are in the ratio [tex]3:5[/tex]. If 9 is added to both the numerator and denominator, they are in the ratio [tex]15:22[/tex]. What is the fraction? Solve algebraically.



Answer :

Certainly! Let's solve this step-by-step.

Given:
- The numerator and denominator of a fraction are in the ratio [tex]\( \frac{3}{5} \)[/tex].
- If 9 is added to both the numerator and the denominator, the new ratio becomes [tex]\( \frac{15}{22} \)[/tex].

We need to find the original fraction.

1. Set up the original fraction:

Let the numerator be [tex]\( 3x \)[/tex] and the denominator be [tex]\( 5x \)[/tex]. Thus, the original fraction is:
[tex]\[ \frac{3x}{5x} \][/tex]

2. Adjust the fraction by adding 9 to both the numerator and the denominator:

If we add 9 to both, the new numerator and denominator will be [tex]\( 3x + 9 \)[/tex] and [tex]\( 5x + 9 \)[/tex], respectively. Therefore, the new fraction is:
[tex]\[ \frac{3x + 9}{5x + 9} \][/tex]

3. Set up the equation with the new ratio:

We know the new fraction is equal to [tex]\( \frac{15}{22} \)[/tex]:
[tex]\[ \frac{3x + 9}{5x + 9} = \frac{15}{22} \][/tex]

4. Cross-multiply to eliminate the fractions:
[tex]\[ 22(3x + 9) = 15(5x + 9) \][/tex]

5. Expand and simplify the equation:
[tex]\[ 66x + 198 = 75x + 135 \][/tex]

6. Move all terms involving [tex]\( x \)[/tex] to one side and constant terms to the other side:
[tex]\[ 66x - 75x = 135 - 198 \][/tex]
[tex]\[ -9x = -63 \][/tex]

7. Solve for [tex]\( x \)[/tex]:
[tex]\[ x = \frac{63}{9} \][/tex]
[tex]\[ x = 7 \][/tex]

8. Calculate the original numerator and denominator:

- Numerator:
[tex]\[ 3x = 3 \times 7 = 21 \][/tex]
- Denominator:
[tex]\[ 5x = 5 \times 7 = 35 \][/tex]

9. Write the original fraction:
[tex]\[ \frac{21}{35} \][/tex]

10. Simplify the fraction if possible:

[tex]\[ \frac{21}{35} = \frac{3}{5} \text{ (already in the simplest form)} \][/tex]

Thus, the original fraction is [tex]\( \frac{21}{35} \)[/tex] which simplifies to [tex]\( \frac{3}{5} \)[/tex] and indeed matches our initial given ratio of 3:5.