The total length of pencils A, B and C is 29 cm. Pencil A is 11 cm shorter than pencil B, and pencil B is twice as long as pencil C. How long is pencil A?
Let B = L
Let A = L - 11
Let C = (1/2)B = (1/2)L = .5L
So we have that
A + B + C = 29
(L -11) + L + (.5)L = 29 simplify
2.5L - 11 = 29 add 11 to both sides
2.5L = 40 divide both sides by 2.5
L = 16
A = L - 11 = 16 - 11 = 5 cm
