Triangle KMS is equilateral. Find KM if KM = x + 6, KS = 2x – 3, and MS = 4x – 21.

thanks bro or sis.

With an equilateral triangle, all three sides are equal.

I'll use KM and KS.

KM = KS   --->              x + 6  =  2x - 3

Subtract x from both sides:  6  =  x - 3

Add 3 to both sides:            9  =  x

So, if  x = 9  and KM = x + 6, how much is KM?

What good manners :)