Question

Cómo hallar el valor de variables

Answer 1

$7y+3x=9$

Variables are the unknows, on this case we have 2 variables

Y and X

variables are always represented by letters

X is

we write the original equation

$7y+3x=9$

now we try to x be alone to solve, then we subtract 7y on both sides

$\begin{gathered} (7y-7y)+3x=9-7y \\ 0+3x=9-7y \\ 3x=9-7y \end{gathered}$

now we divide on both sides by 3 to solve x

$\begin{gathered} \frac{3x}{3}=\frac{9-7y}{3} \\ \\ x=\frac{9-7y}{3} \end{gathered}$

Y is

write original equation

$7y+3x=9$

subtract 3x on both sides to remove 3x on right

$\begin{gathered} 7y+(3x-3x)=9-3x \\ 7y+0=9-3x \\ 7y=9-3x \end{gathered}$

and divide by 7 to solve y

$\begin{gathered} \frac{7y}{7}=\frac{9-3x}{7} \\ \\ x=\frac{9-3x}{7} \end{gathered}$