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
[tex]5x+35y=7z[/tex]...[1]
[tex]z=\frac{5}{7}x+5y[/tex]
4 dollars and 4 pounds is equivalent to 56 crowns
[tex]4x+4z=56y[/tex]
[tex]x+z=14y[/tex]...[2]
Using value of from [1] here in [2]:
[tex]x+\frac{5}{7}x+5y=14y[/tex]
[tex]\frac{12}{7}x=9y[/tex]
[tex]y=\frac{4}{21}x[/tex]
Now:
[tex]z=\frac{5}{7}x+5y[/tex]
[tex]z=\frac{5}{7}x+5\times\frac{4}{21}x[/tex]
[tex]z=\frac{35}{21}x=\frac{5}{3}x[/tex]
1z + 28y = ?
[tex]\frac{5}{3}x+28\times \frac{4}{21}x[/tex]
[tex]=\frac{5}{3}x+\frac{16}{3}x=7x[/tex]
1 pound and 28 crowns is equivalent to 7 dollars.
