Question

If 5 dollars and 35 crowns is equivalent to 7 pounds, and 4 dollars and 4 pounds is equivalent to 56 crowns, 1 pound and 28 crowns is equivalent to how many dollars?

Answer 1

Answer:

1 pound and 28 crowns is equivalent to 7 dollars.

Explanation:

Let the dollars be x , crowns be y and pound be z.

To find = 1z + 28y = ? (value in dollars)

5 dollars and 35 crowns is equivalent to 7 pounds

$5x+35y=7z$...[1]

$z=\frac{5}{7}x+5y$

4 dollars and 4 pounds is equivalent to 56 crowns

$4x+4z=56y$

$x+z=14y$...[2]

Using value of from [1] here in [2]:

$x+\frac{5}{7}x+5y=14y$

$\frac{12}{7}x=9y$

$y=\frac{4}{21}x$

Now:

$z=\frac{5}{7}x+5y$

$z=\frac{5}{7}x+5\times\frac{4}{21}x$

$z=\frac{35}{21}x=\frac{5}{3}x$

1z + 28y = ?

$\frac{5}{3}x+28\times \frac{4}{21}x$

$=\frac{5}{3}x+\frac{16}{3}x=7x$

1 pound and 28 crowns is equivalent to 7 dollars.