Hello There!
<u><em>n - d = 0</em></u>
<u><em>5n+10d = 90</em></u>
<u><em>----------------------</em></u>
<u><em>n-d = 0</em></u>
<u><em>n+2d = 18</em></u>
<u><em>-------------------</em></u>
<u><em>Subtract and solve for "d":</em></u>
<u><em>3d = 18</em></u>
<u><em>d = 6 (# of dimes)</em></u>
<u><em>n = d = 6 (# of nickels)</em></u>
<span>180 degrese or some thing flat</span>
The answer would be each pair of sandals costed $14
$14+$14=28+$3=$31
2/15 + 27/35 = 14+81 /105 = 95/105 = 19/21
so, your answer is 19/21