If x is subtracted from each of 24, 40, 33 and 57, the numbers, so obtained are in proportion. The ratio of (5x + 12) to (4x + 15) is:
Answer & explanation
Correct answer: option 3
The proportion of these numbers,
(24 - x) : (40 - x) :: (33 - x) : (57 - x)
The product of middle terms = product of extreme terms
(40 - x)(33 - x) = (24 - x)(57 - x)
1320 - 40x - 33x + x² = 1368 - 24x - 57x + x²
8x = 48 or x = 6
Thus, (5x + 12) : (4x + 15)
(5 x 6 + 12) : (4 x 6 + 15)
42 : 36 = 14 : 13