Question

If LN = 6x – 5, LM = x + 7, and MN = 3x + 20, find MN.

Answer 1

Answer:

LM = LN + MN [ assuming N is a point between L and M ]

$(x + 7) = (6x - 5) + (3x + 20) \\ x + 7 = 9x + 15 \\ 8x = - 8 \\ { \underline{x = - 1}}$

then find MN:

$MN = 3x + 20 \\ MN = 3( - 1) + 20 = - 3 + 20\\ { \boxed{ \boxed{MN = 17}}}$