Question

Solve for B: AB + 3C = D

Answer 1

If we want to get B by itself, we need to "undo" every operation being done to it. Those operations are (in order):

• Multiplication by A
• Addition with 3C

To undo these then, we'll need to:

• Subtract 3C
• Divide by A

And, since this is an equation, we'll need to do both of those to the right side as well to keep everything equal. Here we go:

AB + 3C - 3C = D - 3C (subtracting 3C)

AB/A = (D - 3C)/A (dividing by A)

B = (D - 3C)/A

And we're done! If you'd like to see it formatted a little nicer, here's this:

$B=\dfrac{D-3C}{A}$