The equation you've provided is:

$3x + 4y = 21$

This is a linear equation in two variables (x and y). To solve for one variable in terms of the other, we can isolate either $x$ or $y$.

Solving for $x$ in terms of $y$:

We can isolate $x$ by moving the $4y$ term to the other side:

$3x = 21 - 4y$

Now, divide by 3:

$x = \frac{21 - 4y}{3}$

Solving for $y$ in terms of $x$:

Alternatively, to solve for $y$, move the $3x$ term to the other side:

$4y = 21 - 3x$

Now, divide by 4:

$y = \frac{21 - 3x}{4}$

These are the general solutions for $x$ and $y$ in terms of each other. If you have a specific value for either $x$ or $y$, you can substitute that in to find the corresponding value for the other variable.

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Related Questions:

1. How do you graph the equation $3x + 4y = 21$?
2. What is the slope and y-intercept of the equation?
3. How can we solve this equation using substitution or elimination if we have another linear equation?
4. What happens if the equation is given in a different form, such as slope-intercept form?
5. How would you solve a system of linear equations with this equation and another equation?

Tip:

To solve linear equations efficiently, always try to isolate one variable first, and then substitute or solve for the other.