algebra problem

[newtomaths]

in the equation 10-10k=100 how do you come up with the answer -6 only way i can think of working this out is 10-10k-10=100-10
-k=90 so -1*-k=k and -1*90=-90 can anyone help.

 

[Denis]

in the equation 10-10k=100 how do you come up with the answer -6 only way i can think of working this out is 10-10k-10=100-10
-k=90 so -1*-k=k and -1*90=-90 can anyone help.

I think you need to first learn how to solve.

Add 10k: 10 = 100 + 10k
Subtract 100: -90 = 10k
Divide by 10: -9 = k

If answer is -6, then equation is 40 - 10k = 100