Math problem...

[Xero]

Hey uhhh im in like 8th grade so im kinda stupid in math (well for my grade being in algebra which i am is good) but anyway i cant seem to figure out this: 2x + 4y = 69380. I never did any problems with two variables so im just like... yeaaaha i can right about solve that... But anyway, i gotta find what x and y are. Thanks! THe quicker i get the answer the better...

[HarryW]

If you have 2 variables, then you will need two equations in order to solve the set of equations. There are an infinite number of possible values otherwise, which you can see by rearranging the equation and plotting a graph (of x against y).

2x + 4y = 69380 - initial eqn

x + 2y = 34690 - divide both sides by 2

2y = 34690 - x - subtract x from both sides

y = (34690 - x) / 2 - divide both sides by 2

y = 34690/2 - x/2 - expand the brackets

y = 17345 - x/2 - simplify


If you draw a graph for y=17345-x/2 you will see that it is a straight line. If you take the x and y coordinates of any point on that line, they will be valid in your above equation.

If you had another equation to go with it, such as 4x + y = 50000, then you could solve it by substitution or some other method. If you need a particular method explained just say. If you've got to solve this for x and y then you will almost certainly have been taught some method of doing so.