2x-y= -14 x=3y=7

Question

twice a first number decreased by a second number is -14. the first number increased by three times the second number is 7. find the numbers

Answer 1

Hello Taj,

 

I think you might have written the equation wrong. "Increased by" should mean an addition sign so if the equation is as follows we can solve it:

 

2x-y=-14

x+3y=7

 

To do this, we simply add the two equations together to get:

 

3x+2y=-7

 

From here, we solve for x or y, but let's choose x.

 

3x=-2y+7

x=(-2y+7)/3

 

Now that we have x, we simply plug it into the original equation to find y:

 

2((-2y+7)/3)-y=-14

((-4y+14)/3)-y=-14  We multiplied the two

((-4y+14)/3)+14=y   We moved the y and 14 to get y by itself

-4y+14+42=3y   We multiplied everything by 3 to get rid of the division of 3

56=7y

8=y

 

Now, we can plug in y to solve for the numerical x:

 

2x-8=-14

2x=-6

x=-3

 

I hope this helps. :)