Question

When we multiply 21/43 by a number we get 12/23. What is the number

Answer 1

letter number be X

$x \times \frac{21}{43} = \frac{12}{23 } \\ x = \frac{12}{23 } \times \frac{43}{21 } \\ x = \frac{3 \times 43}{23 \times 7 } \\ x = \frac{129}{161}$

Hope it helps