If the three sides of a triangle are a,b, and c, it must be that if you add any two sides, the number you get must be greater than the third side, that is a + b > c a + c > b b + c > a In your case, a = 8, b = 10, and c = x 8 + 10 > x 8 + x > 10 10 + x > 8 Simplifying, we get 18 > x x > 2 x > -2 The first one answers your question. 18 is greater than x. Edwin