Problem Solving

BTGmoderatorDC wrote:If 0.25 + x = y and y/x = 0.2, then y =

A. -1
B. -1/2
C. -1/4
D. -1/8
E. -1/16

Take: y/x = 0.2,
Multiply both sides by x to get: y = 0.2x
Multiply both sides by 5 to get: 5y = x

Now take: 0.25 + x = y
Multiply both sides by 4 to get: 1 + 4x = 4y

Take: 1 + 4x = 4y and replace x with 5y to get: 1 + 4(5y) = 4y
Simplify: 1 + 20y = 4y
Subtract 20y from both sides to get: 1 = -16y
Divide both sides by -16 to get: -1/16 = y

Answer: E

Cheers,
Brent

BTGmoderatorDC wrote:If 0.25 + x = y and y/x = 0.2, then y =

A. -1
B. -1/2
C. -1/4
D. -1/8
E. -1/16

OA E

Source: Magoosh

We see that y = 0.2x; thus:

0.25 + x = 0.2x

0.25 = -0.8x

25 = -80x

x = 25/-80 = -5/16

So y = 0.2(-5/16) = -1/16.

Answer: E