An algebra problem by Wildan Bagus Wicaksono

Algebra Level 2

Budi is a male student and Wati is a female student. Both of them are in grade IX. Currently they are sitting in class IX at a school. They record a lot of grade IX students in their school. Wati noted that $\frac{3}{20}$ of the total students in class IX other than herself is male. Budi noted that $\frac{1}{7}$ of the total students in class IX other than himself is male. How many male class IX students are in their school?

The answer is 21.

1 solution

Wildan Bagus Wicaksono
Jul 3, 2017

$n$ =Many students of class IX

$l$ = Many male students in class IX

According to Wati's note, $\frac{3}{20}$ of the total students in class IX other than himself is male.

$\frac{3}{20}$ $(n - 1) = l$

$n = \frac { 20 }{ 3 } l+1$

According to Budi's note, $\frac{1}{7}$ of the total students in class IX other than himself is male.

$\frac{1}{7}$ $(n - 1) = l - 1$

$\frac { 1 }{ 7 } \left( \frac { 20 }{ 3 } l+1-1 \right) =l-1$

$l-\frac { 20 }{ 21 } l=1$

$\frac { 1 }{ 21 } l=1$

$l=21$

An algebra problem by Wildan Bagus Wicaksono

The answer is 21.

1 solution

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