6x+7y=20, when y=2x

Question

What is 6x+7y=20 when y=2x?

Answer 1

6x+7y=20, when y=2x

 

It tells you that y=2x, so wherever there is a "y" in the

problem simply replace it with 2x.  Then solve the

equation for x.  Once you find the value of x, you can

then multiply that value by 2 to find the value of y.

 

6x + 7(2x) =  20  multiply the 7 through the parenthesis

6x + 14x = 20     add the like terms together

20x = 20             divide both sides by 20

20x/20 = 20/20

x = 1

 

Now that you have the value x=1 then since y = 2x

then y = 2(1) = 2

 

Answer:  x=1, y = 2

 

To check the answer, replace x and y

with their respective values and see if

the equation balances.

 

6(1) + 7(2) = 20

6 + 14 = 20

20 = 20

Answer is correct.