CTET Maths - Algebra
16. If 50% of (x - y) = 30% of (x + y), what per cent of x is y?
- Option : C
- Explanation : 50% of (x-y) = 30% of (x + y)
⇒ (50/100) (x - y) = (30/100) (x + y)
⇒ 5x - 5y = 3x + 3y ⇒ 2x = 8y ⇒ x = 4y
Required percentage = y/x × 1000%
= (y/4y) x 100% = 25%
17. If 35 is subtracted from a number reduces to its 80%. What is 4/5th of that number?
- Option : D
- Explanation : Let the number be x.
Then,x- 35= (80/100)x
x-(4/5)x = 35 ⇒ x/5 = 35 ⇒ x = 175
Now, 4/5 of x = 4/5 × 175 = 140
18. A number is first increased by 10% and then decreased by 10%, then the number
- Option : C
- Explanation : Let the number be 100. After increasing by 10%, the number = 110% of 100 = 110 . After decreasing by 10%, the number = 90 % of 110 = 99 . Decrement in number = 100 -99 = 1 . Percentage decrease = (Decrease in number / Original number ) x 100% = (1/100) x 100% = 1%
- Option : C
- Explanation : CP = 75000 Rs. Loss percentage = 15% . SP = (100 -15)% of 75000 . = 85/100 x 75000 = 63750 Rs
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