If 50% of (x-y)=30% of (x+y) then what percent of x is y?

7.  If 50% of (x-y)=30% of (x+y) then what percent of x is y?

A. 25%

B. 50%

C. 75%

D. 100%

ANS: A

EXPLANATION:

50/100 (X-Y) = 30/100 (X+Y)

1/2 (X-Y) = 3/10 (X+Y)

½ X - 3/10 X = 3/10 Y + 1/2 Y

2/10 X = 8/10 Y

Y = ¼ X

¼= 25%

8. 30 percent of a number is 15 less than 3/5^th of a number. What is the number?

A. 48

B. 52

C. 50

D. 70

ANS: C

EXPLANATION:

30/100 X = 3/5 X – 15

 3/10 X – 3/5 X = 15

3/10 X = 15

X = 50