QA – Placement Quizzes | Algebra | Question 10

4/15 of 5/7 of a number is greater than 4/9 of 2/5 of the same number by 8. What is half of that number?
(A) 630
(B) 63
(C) 315
(D) 105


Answer: (C)

Explanation: Let the number be x. Then,
4/15 of 5x/7 = 4/9 of 2x/5 + 8
4/15 * 5x/7 = 4/9 * 2x/5 + 8
4x/21 = 8x/45 + 8
x/21 = 2x/45 + 2
x/21 = (2x + 90)/45
45x = 21(2x + 90)
45x = 42x + 90*21
3x = 90*21
x = 30*21 = 630.

Half of the number will be x/2

x/2 = 630/2 = 315.

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