You can solve all of these the same way, it's just some of them take a little more work.

When you're told to solve for a variable, you want to isolate it; that is, get it alone on one side of the equals side. So, with your more basic equations (like 'd=rt'), you can do this easily in one step (in this case, divide each side by t, giving you d/t = r).

And, usually, each step takes the form of dividing by something (like the d=rt case) or subtracting something (like how you solve K=C+273). Later on, you may start squaring both sides or a few other things, but for right now, division & subtraction are your friends.

Your more difficult questions simply have more steps, but they're still just division/subtraction. Take the first one (V=1/3 Bh). The first thing I would do would be to get rid of the 1/3 from the right side. So you can do that by dividing each side by 1/3...which happens to be exactly the same thing as multiplying each side by 3. So, once you do that, you have 3V = Bh. But this is really similar to d=rt: you just want to move the h over. So divide each side by h...and you get 3V/h = B. Problem solved.

Your second equation would be harder, except you're given a bunch of numbers to plug in. Just remember the distributive law: a(b+c) = ab+ac, and the rest should fall into place. Try to figure it out and let me know what you get (or, if you run into a problem, let me know that).

I like the equations they are having you work with. Whatever text you are using is probably a good one.

You know, I was thinking that too.

Hmm...

Does it matter what step you do first? Like in:

P = 2l + 2w (for l)

would it matter if I subtracted by 2w or divided by two first?

In the problem

A = 2(lw + wh + lh), solve for l, given w = 5, h = 3, and A = 158

l would be...... I have no idea. can't do it at all.

you can usually do it in whatever order you want. So you can subtract or divide first. I would probably divide, but that's just personal preference.

I'll give you the first three steps. Simply plug in the numbers you have.

A = 2(lw + wh + lh), solve for l, given w = 5, h = 3, and A = 158

you know that A = 128, so that means that 128 = 2(lw+wh+lh). Then, you know that h = 3, so this means that 128 = 2(lw+w*3+l*3). Finally, w = 5, so you have 128 = 2(l*5 + 5*3 + l*3). Now you should be able to move things around.