Practicing Success
x is the 4th proportional to 12, 16 and 5; and 20, y, 15,21 are in proportion. Then the value of (6x - y) is: |
9 18 13 12 |
12 |
12 : 16 :: 5 : x, 20 : y :: 15 : 21 ⇒ 12x = 16 x 5 ⇒ 15y = 20 x 21 ⇒ 12x = 80 ⇒ 15y = 420 ⇒ x = \(\frac{40}{6}\) ⇒ y = 28 ⇒ (6x - y) = 6 x \(\frac{40}{6}\) - 28 ⇒ 40 - 28 = 12. |