Question

Write the equation 8y = 1/12x – 0.8 in standard form. Identify A, B, and C.

A. 480x + 5y = –48 where A = 480, B = 5, and C = -48


B. 480x – 1y = –48 where A = 480, B = –5, and C = -48


C. 5x – 480y = 48 where A = 5, B = –480, and C = 48


D. 1x + 96y = 9.6 where A = 1, B = –96, and C = 0.8

Answer 1

Naswer C:
`5x-480y=48`

Explanation:

Let's first write all the coefficients in fraction form, noticing that 0.8 is the same as
`(8)/(10) =(4)/(5)`, and then group the term in x and the term in y on one side of the equal sign, moving the pure numerical coefficient to the other side:

`8y=(1)/(12) x-(4)/(5) \\0=(1)/(12) x-8y-(4)/(5)\\(4)/(5) =(1)/(12) x-8y`

Now find the LCD for the existing denominators (5 and 12). This is: LCD = 60

Use the LCD we just found, to multiply both sides of the equation, so as to get rid of all denominators in the equation:

`(4)/(5) =(1)/(12) x-8y\\60*(4)/(5) =60*((1)/(12) x-8y)\\12*4=(60)/(12) x-60*8y\\48=5x-480y\\5x-480y=48`

notice that our equality matches answer C provided.