Question

15x+40y=32

Answer 1

Is this a continuation of the previous question?

Answer 2

yes, but x and y are different this time, please could you show a step by step way to solve this so I can understand how to do it.

Answer 3

Do you know how to isolate x (or y)?

Answer 4

no

Answer 5

ouch.

Answer 6

x=(32-40y)/15
y=(32-15x)/40
sub y into x
x=(32-40(32-15x/40))/15
15x=32-1280-15x
30x=32-1280
30x=-1248
x=-41.6
40y=32-15(-41.6)
40y=32+624
y=592/40
y=14.8

Answer 7

Just remember that whatever you do to one side of the equation you must do to other side as well. For this example, I'll go with isolating x:

15x+40y=32
15x=32-40y (I subtracted 40y from both sides)
x = (32-40y)/15 (divided both sides by 15 to x alone)

Now you know what x is in terms of y. If you plug this into your original equation you get a new equation which only has one type of variable: y. Once you figure out what y is, plug it into the original equation and solve for x.

Answer 8

@stevenator: It appears that your signs of x and y values are backwards but otherwise correct

Answer 9

I punched it in and got -32 instead of 32

Answer 10

trial and error i put in 16.4 for y, and got 32, does it work like that or do i have to go through the equation with it to find y

Answer 11

You have to go through the equation to solve for both x and y. What did you get for x during your trial and error run?

Answer 12

i used X from steve's reply (x=-41.6)

Answer 13

I see...you just found another solution to the problem. Trial and error is one way to do these but I doubt your teacher wants you to guess at values. Solving the equation is actually faster once you get the hang of it.

Answer 14

so i typed 15X-41.6 +40X16.4

Answer 15

the answers are the opposites of mine, so x=41.6 and y=-14.8

Answer 16

yes