try to write mathematical equations from the information provided.
Let us call 1 of the numbers x and the other y. now try to do it and I will correct you.
The sum of two numbers is 42. One number plus two times the other number is 57. What are the two numbers?
I need the formula as well to help me learn to disect these problems. I have a block or something. Is there an easy way to learn this!!!! Age problems are worse!
OK, no problem,
First is important that you understand where these equations come from.
x + y = 42
x + 2y = 57
Once you understand how I wrote these equations from the given information we can solve this system of equations using substitution or subtracting the top equation from the bottom and then using substitution.
..(x + 2y = 57)
-(x + y = 42)
........y = 15
now plug in y=15 into either equation above and solve for x. Give it a try and I will correct you if you make a mistake.
x-y=80
3x+4y=-334
Lets solve for x in terms of y on the first equation and then plug it in to the second.
x-y=80
x=y+80 eq1
3x+4y=-334 (plug in eq1 for x)
3(y+80)+4y=-334
3y+240+4y=-334
7y=-574
y=-82
now plug in y to the first equation
x-(-82)=80
x=-2
Here is one way.
"The sum of two numbers is 42. One number plus two times the other number is 57. What are the two numbers?"
Let x = one number
So, 42-x is the other number
x +2(42-x) = 57
x +84 -2x = 57
x -2x = 57 -84
-x = -27
x = 27
42-x = 42-27 = 15
Therefore, the two numbers are 15 and 27. ----answer.
----------------
Another way.
Let x = one number
And y = the other number
x +y = 42 ----(i)
x +2y = 57 ----(ii)
From (i), x = 42-y
Substitute that into (ii),
(42-y) +2y = 57
42 -y +2y = 57
-y +2y = 57 -42
y = 15
So,
x = 42-y = 42-15 = 27
Therefore, the two numbers are 15 and 27.
Or,
(ii) minus (i),
y = 15 ----right away.
etc...