if 2x+4y=20 and 3x+5y=15, what do x and y equal?

Answer 1

First notice that this is a system of equations: You can solve by 1) graphing 2) a matrix 3)substitution 4)elimination.

Lets use substitution:

1. Solve for y in equation 1.

2x+4y=20 *subtract 2x
4y=20-2x *divide by 4
y=5-1/2x

2. Now plug in the new y value for y in the second equation and solve for x.

3x+5(5-1/2x)=15 *distribute
3x+25-5/2x=15 *combine like terms
25+1/2x=15 *isolate the x term by subtracting 25
1/2x= -10 *divide by one half(calculator is your friend)
x= -20

3. Now that you know x= -20 you can plug the new x value into the equation and solve for y!

3(-20)+5y=15
-60+5y=15 *isolate by adding -60
5y=75 *divide by 5
y=15

So there you have it! x= -20 and y= 15! You can take either equation and solve for the variable of your choice. Just make sure to check your work by plugging in the values of x and y into each equation.

Answer 2

If you multiply 2x + 4y = 20 times 3
and 3x + 5y = 15 times 2, you get
6x + 12y = 60 and
6x + 10y = 30 and subtracting the equations you get
2y = 30 therefore y = 15
Substituting 15 for y in the equations, you get
x = -20

Answer 3

2x - y =8 3x - y = 6 2x - y - 8 =0 3x - y - 6 =0 utilizing subtraction approach, 2x - y - 8=0 -3x + y + 6=0 -x - 2 = 0 -x = 2 x = -2 change -2 to x in between the equations to get the cost of y. 2(-2) - y = 8 -4 - y = 8 -y = 8+4 y = - 12

Answer 4

There diff ways of doing... but i'll do it the way i like best.
You take one of the equations and solve for one of the variables (x or y) I am going to use equation one and solve for x.
2x + 4y = 20
subtract 4y from both sides
2x = 20 - 4y
divide by 2
x = 10 - 2y
Now using this for x plug it into the other equations and so you have 3(10 - 2y) +5y = 15
now distribute the 3 so you get
30 - 6y + 5y = 15
subtract 30 from both sides
-6y + 5y = -15
combine like terms so you have
-y = -15
divide both sides by -1 so you get
y = 15
Now that you have solved for y, use it and plug this value of y into the first equation and solve for x . that is
2x + 4(15) = 20
mulitply 4 and 15 to get
2x + 60 = 20
subtract 60 from both sides to get
2x = -40
divide both sides by 2
x = -20

If you need further explanation... im me or email me

EDIT: Final answer x = -20 and y = 15 and if you need to write it in coordinates or as a point then it is (-20, 15)

Answer 5

To solve you need to get one of the variables by itself on one side.
2x + 4y = 20 Subtract 4y from both sides and you have
2x = 20-4y Now divide both sides by 2.
x = 10 - 2y

Now replace the x in the second equation with (10-2y)
3(10-2y) + 5y = 15. or 30-6y + 5y = 15 or 30 - y = 15.
Now subtract 30 from each side.
- y = -15 So y = 15
If x = 10-2y then x =10-30 = -20

Answer 6

your y= 15 and x= -20

Answer 7

y=15 and x=-20

Answer 8

x = -20 and y = 15

Answer 9

2x + 4y = 20 (multiply by -3)
3x + 5y = 15 (multiply by 2)

-6x - 12y = -60
6x + 10y = 30 (add equations)

0x - 2y = -30 (x's cancel, so you're left with -2y =-30. Divide both sides by -2)

y=15 (substitute it back in to one of the original equations)

2x + 4(15) = 20
2x +60 = 20
2x = -40
x= -20

Y= 15 X=-20

Answer 10

2x + 4y = 20
3x + 5y = 15

Firs isolate one of the variables in one of the equations
2x + 4y = 20
2x = 20 - 4y
x = 10 - 2y

Then plug the variable value into the other equation and isolate for the other variable
3x + 5y = 15
3(10 - 2y) + 5y = 15
30 - 6y + 5y = 15
-y = -15
y = 15

Plug the other variable into one of the equations to solve for x
2x + 4y = 20
2x + 4(15) = 20
2x + 60 = 20
2x = -40
x = -20

x = -20; y = 15