Solve for the variable a

Question

I need help on how to solve for the variable a in a equation that has 2 other variables.

What are the steps to solve the following equation

a+b-9=p

solve for, a

Answer 1

a+b-9=p

Subtract b from both sides:

a - 9 = p - b

Add 9 to both sides:

a = p - b + 9

We don't know either p or b, but if we did, we could use this equation to determine the value of a.

Solving such equations isn't any different than when numbers are involved. It's the same process.

By the way, this is called a literal equation. You are not solving for a number, but instead you seek another equation. This occurs frequently.

Here is an example: circumference = diameter times pi, or

C = π × D

But you might have the circumference and want to know the diameter:

D = C / π

Or you might have C and D and want to see what π is:

π = C / D

just to see how close you get to the actual value.

There are lots of such equations, and often you need the value of a variable that is usually a given value in a common formula. Algebra to the rescue!

Answer 2

Hi Lexii!

When you’re solving for a variable with other variables in the equation, just remember that those variables have the exact same rules as numbers. Pretend you are solving this equation with only one variable, and put numbers in place of the others. What would your steps be? Now, try the exact same steps with the variables instead of numbers.

Remember: you won’t get a fully simplified solution. Your answer will have the variable you’re solving for on one side, and the other variables on the other side.