<p>If y is inversely proportional to x and =15 when x = 5, what is the value of y when x = 25?</p>
<p>The answer is 3, but I really couldn't get it.. Please explain me..</p>
<p>thanks in advance!</p>
<p>For inverse proportions, just remember the formula below:</p>
<p>y = k/x, where k is a constant. </p>
<p>In this case, </p>
<p>y = 15 when x = 5. Plug those two given numbers into the equation.</p>
<p>15 = k/5 => k = 75 => y = 75/x. </p>
<p>Now, you want to find y when x = 25. </p>
<p>y = 75/x (equation from above) </p>
<p>plug-in: </p>
<p>y = 75/25 => y = 3.</p>
<p>IceQube, thank you!</p>