# Thread: Scientific Equation - Solve for Variable

1. ## Scientific Equation - Solve for Variable

Please can someone explain how this answer was achieved?

Solve for C

S=C+RC

The answer they have is:

C= 5
-------
1 + R

2. ## Scientific Equation - Solving for a variable.

Here's the question:

Solve for b.

A= 1 * (a + b)h
_
2

Just for clarity that is 1 over 2 (as in a half, I don't know how to make it look like it does on my page using my computer keyboard).

The answer they gave is:

2A - ah
--------
h

I got...

2A - a
--------
h

I'm confused about how the h ended up on the top and the bottom of the equation when you would be simply multiplying by 1 over h or should you be working out the expression so that is becomes ah + bh first?

3. Originally Posted by suddenlysmarter
Please can someone explain how this answer was achieved?

Solve for C

S=C+RC

The answer they have is:

C= 5 .........<<<<<< this should be S
-------
1 + R

\begin{aligned}S&= C + RC \\
S&=C(1+R)\\\dfrac{S}{1+R}&=C\end{aligned}

4. Originally Posted by suddenlysmarter
Here's the question:

Solve for b.

A= 1 * (a + b)h
_
2

Just for clarity that is 1 over 2 (as in a half, I don't know how to make it look like it does on my page using my computer keyboard).

The answer they gave is:

2A - ah
--------
h

I got...

2A - a
--------
h

I'm confused about how the h ended up on the top and the bottom of the equation when you would be simply multiplying by 1 over h or should you be working out the expression so that is becomes ah + bh first?
\begin{aligned}A&=\dfrac12 (a+b)h\\
\dfrac{2A}h&=a+b \\
\dfrac{2A}h - a &=b \\
\dfrac{2A}h - \dfrac{ah}h &=b \\
\dfrac{2A-ah}h &=b \end{aligned}