The sum of two numbers is 16 and their difference is 20. What are the two numbers?

how do I figure this out?

3 Answers
Mar 21, 2018

18 and -2

Explanation:

Let the numbers be m and n

The sum of the numbers is 16 -> m+n =16

Their difference is 20 -> m-n=20

Thus we have a system of simultaneous equations:

m+n =16 [A]

m-n =20 [B]

[A]+[B] -> 2m =36

:. m=18

m=18 in [B] -> 18-n =20

n=18-20 =-2

Hence our two numbers are 18 and -2

Check:
18+(-2) = 18-2=16
18-(-2) = 18+2 =20

Mar 21, 2018

The numbers are 18 and -2.

Explanation:

Let x be the first number and let y be the second number.
x + y =16
x-y = 20
After adding the two equations:
2x = 36
x = 18
Substituting 18 for x to find y:
18 + y=16
y = -2

Mar 21, 2018

The numbers are 18 and -2.
You should set up equations to solve them.

Explanation:

The ones I did were:
a-b=20, which represents that the difference was 20.
a+b=16, which represents that the sum of the two numbers is 16.
You should then isolate a variable(I isolated a).
=> a=16-b and a=20+b, because a must equal a.
So, 16-b=20+b
Add -b to b => 16=2b+20
Subtract 20 from both sides => 2b=-4
Divide by 2 => b=-2
Since b=-2, plug b into an equation.
=> a+(-2)=16 => a-2=16
Add 2 to both sides => a=18
b=-2, a=18