1. Rewriting Equations

I have to solve for y . No given values
I already tried solving this but I just can't solve the fraction. I tried multiplying the reciprocal on both sides but I don't know if I have to make 20 a fraction
$\displaystyle -\frac{5}{4}&x+&5y&=20$

2. Re: Rewriting Equations

$\displaystyle -\frac{5}{4}x+5y=20$

$\displaystyle 5y=20+\frac{5}{4}x$

$\displaystyle y=\frac{20+\frac{5}{4}x}{5}$

$\displaystyle y=4+\frac{x}{4}$

3. Re: Rewriting Equations

Originally Posted by pickslides
$\displaystyle -\frac{5}{4}x+5y=20$

$\displaystyle 5y=20+\frac{5}{4}x$

$\displaystyle y=\frac{20+\frac{5}{4}x}{5}$

$\displaystyle y=4+\frac{x}{4}$
Whats going on with the fraction in the second step? is it being simplified by 5?

4. Re: Rewriting Equations

$\displaystyle -\frac{5}{4}x+5y=20$

$\displaystyle 5y=20+\frac{5}{4}x$

multiply every term by 4 to clear the fraction ...

$\displaystyle 20y=80+5x$

divide every term by by 20 ...

$\displaystyle y = 4 + \frac{x}{4}$

5. Re: Rewriting Equations

Originally Posted by skeeter
$\displaystyle -\frac{5}{4}x+5y=20$

$\displaystyle 5y=20+\frac{5}{4}x$

multiply every term by 4 to clear the fraction ...

$\displaystyle 20y=80+5x$

divide every term by by 20 ...

$\displaystyle y = 4 + \frac{x}{4}$
I got everything until you have to divide by 20.

80/20 = 4
5x/20 = Lost

6. Re: Rewriting Equations

Originally Posted by vaironxxrd
I got everything until you have to divide by 20.

80/20 = 4
5x/20 = Lost
$\displaystyle \frac{5x}{20} = \dfrac{5x}{5 \times 4}$

Cancel 5 to get x/4

7. Re: Rewriting Equations

Originally Posted by e^(i*pi)
$\displaystyle \frac{5x}{20} = \dfrac{5x}{5 \times 4}$

Cancel 5 to get x/4
Got it , I din't know I could do that,
Thanks