Answer:
C. 6
Explanation:
∆ABC and ∆ADE are similar triangles.
AB/AC = AD/AE
(x - 1 + x + 2)/(15 + 24) = (x - 1)/15
(2x + 1)/39 = (x - 1)/15 Multiply each side by 39
2x + 1 = 39(x - 1)/15 Multiply each side by 15
15(2x + 1) = 39(x - 1) Distribute 15 and 39
30x + 15 = 39x - 39 Add 39 to each side
30x + 54 = 39x Subtract 30x from each side
54 = 9x Divide each side by 9
x = 6
Check:
(6 - 1 + 6 + 2)/(15 + 24) = (6 - 1)/15
13/39 = 5/15
⅓ = ⅓