# Math

posted by .

If y varies directly as x and y=3 when x=10, find x when y=8? Can you please show me step by step solution for this problem?

• Math -

Whenever you have a statement such like yours,
"If y varies directly as x "
you can form the equation
y = kx , where k is a constant

sub in the given: y=3 , x=10 to find k
3 = k(10)
k = 3/10

so your equation is y = (3/10)x

then when y = 8

8 = (3/10)x
80 = 3x
x = 80/3

btw, if it has said" y varies inversely as x" your equation would have been
y = k(1/x), but you would follow the same steps of subbing in the given data to find k

• Math -

Thank you so much that helps a lot!

• Math -

welcome

## Similar Questions

1. ### Greens Theorem

Can someone show me step by step how to work this problem out please. Let C be the triangle with vertices (0,0), (1,0), and (1,2). Find the following line integral by two methods, directly and using greens theorem. 2xy^2dx + yx^2dy …
2. ### Pre-Algebra [urgent!]

I can't find the solution to this problem; can someone please show me how to solve it step-by-step?
3. ### Physics

I'm trying to rearange this 0 = Xo + 2^-1 a t^2 for t I've been told that it is (a^-1 2x)^(2^-1) but I do not see how please show me step by step how you get that 0 - Xo = Xo - Xo + 2^-1 a t^2 (-Xo = 2^-1 a t^2) a^-1 2 (a^-1 (2-Xo) …

I need help with this problem ! 5 2/5 - 3 4/5= ?
5. ### Chemistry

If 8.5g of pure ammonium phosphate , (NH4)3PO4(s), is dissolved in distilled water to make 400mL of solution, what are the concentrations (in moles per litre) of ions in the solution. How would I solve this type of stoichiometric problem. …
6. ### Chemistry

If 8.5g of pure ammonium phosphate , (NH4)3PO4(s), is dissolved in distilled water to make 400mL of solution, what are the concentrations (in moles per litre) of ions in the solution. How would I solve this type of stoichiometric problem. …
7. ### math

The equation: T= 2* pi* sqrt(2/3L/9.8) Solve for L. Please show the solution step by step. The square root is giving me trouble in my solution. Thanks for your help.
8. ### Math

I need help solving the problem not the answer. (Multiple Choice) The steps below show the incomplete solution to find the value of x for the equation 7x + 8 − 3x = −6 + 10: Step 1: 7x + 8 − 3x = −6 + 10 Step 2: 7x + 8 − …