19. [tex]\(\frac{1}{4}\)[/tex] of a certain number is added to [tex]\(4 \frac{1}{3}\)[/tex]. The sum is the same as when [tex]\(\frac{1}{3}\)[/tex] of it is subtracted from [tex]\(20 \frac{2}{3}\)[/tex]. Find the number.



Answer :

To find the number, let us denote it by [tex]\( x \)[/tex].

According to the problem, [tex]\(\frac{1}{4}\)[/tex] of [tex]\( x \)[/tex] is added to [tex]\( 4 \frac{1}{3} \)[/tex]. The expression for this part is:
[tex]\[ \frac{1}{4}x + 4 \frac{1}{3} \][/tex]

We can convert the mixed number [tex]\( 4 \frac{1}{3} \)[/tex] into an improper fraction:
[tex]\[ 4 \frac{1}{3} = 4 + \frac{1}{3} = \frac{12}{3} + \frac{1}{3} = \frac{13}{3} \][/tex]

Now, substituting this back in, the left-hand side of the equation is:
[tex]\[ \frac{1}{4}x + \frac{13}{3} \][/tex]

The problem also states that this sum is the same as when [tex]\(\frac{1}{3}\)[/tex] of [tex]\( x \)[/tex] is subtracted from [tex]\( 20 \frac{2}{3} \)[/tex]. The expression for this part is:
[tex]\[ 20 \frac{2}{3} - \frac{1}{3}x \][/tex]

Similarly, convert the mixed number [tex]\( 20 \frac{2}{3} \)[/tex] into an improper fraction:
[tex]\[ 20 \frac{2}{3} = 20 + \frac{2}{3} = \frac{60}{3} + \frac{2}{3} = \frac{62}{3} \][/tex]

Now, substituting this back in, the right-hand side of the equation is:
[tex]\[ \frac{62}{3} - \frac{1}{3}x \][/tex]

We set up the equation as given in the problem:
[tex]\[ \frac{1}{4}x + \frac{13}{3} = \frac{62}{3} - \frac{1}{3}x \][/tex]

To solve this equation, first clear the fractions by finding a common denominator for all terms. The common denominator for 4 and 3 is 12. Multiply every term by 12 to clear the fractions:
[tex]\[ 12 \left( \frac{1}{4}x + \frac{13}{3} \right) = 12 \left( \frac{62}{3} - \frac{1}{3}x \right) \][/tex]

Applying the multiplication:
[tex]\[ 3x + 4 \cdot 13 = 4 \cdot 62 - 4x \][/tex]

Simplify each term:
[tex]\[ 3x + 52 = 248 - 4x \][/tex]

Now, combine like terms:
[tex]\[ 3x + 4x + 52 = 248 \][/tex]
[tex]\[ 7x + 52 = 248 \][/tex]

Next, isolate [tex]\( x \)[/tex] by subtracting 52 from both sides:
[tex]\[ 7x = 196 \][/tex]

Finally, divide by 7:
[tex]\[ x = 28 \][/tex]

Thus, the number is:
[tex]\[ \boxed{28} \][/tex]