Ashvin H.
asked 12/10/18The sum of two numbers are 18 and their difference is 4 what are the two numbers?
Plz help and btw its bigger number subtacted by smaller number
1 Expert Answer

Carrie C. answered 12/10/18
Credentialed Math and Science Teacher for over 4 years
The sum means to add two numbers so we can write : x + y = 18
Then, their difference is 4 which can be written : x - y = 4
The best way to determine this is to set one of the variables on one side of an equation to use in the second equation. This takes a bit of algebra.
x + y = 18 can be rearranged to x = 18 - y OR y = 18 - x : either of these gives you an equation to plug in to the second equation to find one of the variables.
x - y = 4 , from the equation we rearranged before, y = 18-x so we can plug this equation in for y
x - (18-x) = 4
Now we only have x to solve for :
x-18 +x = 4 (the second x becomes a plus because of the negative on the outside of the parenthesis.
then if we add18 on both sides:
x +x = 4 +18
simplify : 2x = 22
x = 11
Then we plug 11 into the previous equations we started with:
x + y = 18 -----> 11 + y =18 -------> y = 7
x - y = 4 --------> does 11-7 = 4? Yes! So we found out that x = 11 and y = 7
Raieghlynn M.
Is their any other way to do this for younger kids maybe 5th and younger? If so update pls.08/10/20
Trinity B.
its 11 and 710/14/20
Aaydian P.
ok thanks11/05/20
Jeremiah T.
im in 6th grade and i don't understand the queoiton11/09/20
Jeremiah T.
quetion11/09/20
Zoey W.
I Don’t get it12/03/20
Emma K.
Its hard but the answer is 11 and 412/18/20
Nikki R.
GUYS ADD THEN SUBTRACK!!01/12/21
Willow Y.
the answer is 11 and 401/18/21
Anthony V.
It's 11 and 7 and i'm in 4th grade.01/24/21
Zachary J.
Thanks Anthony V.!02/02/21
Destiny W.
im 20 and its 11 and 7 :)02/10/21
Jatwan G.
its 11 and 7 and im in 5th02/26/21
Sean S.
how are you an expert its 11 and 704/15/21
Alexa K.
11 and 7 it is04/19/21
Alexa K.
11 and 7 it is - the wise yoda04/19/21
Bailynn R.
thanks I was having trouble09/23/21
Magnificent P.
this is not helping me at all y'all10/08/21
Magnificent P.
Alexa k. help me all thanks10/08/21
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Anjelica J.
hi09/22/20