How do you solve 10/k=8/410k=84?

1 Answer
Sep 3, 2016

k=5k=5

Explanation:

We have one fraction equal to another. In this situation we can color(blue)"cross-multiply"cross-multiply to solve.

rArrcolor(blue)(10)/color(red)(k)=color(red)(8)/color(blue)(4)10k=84

Now cross-multiply(X) the values on either end of an 'imaginary' cross and equate them. That is multiply the color(blue)"blue"blue values together and the color(red)"red"red values together and equate them.

rArrcolor(red)(8k)=(color(blue)(10)xxcolor(blue)(4))rArr8k=408k=(10×4)8k=40

now divide both sides by 8 to solve for k.

rArr(cancel(8)^1 k)/cancel(8)^1=(cancel(40)^5)/cancel(8)^1rArrk=5