the sum of two numbers is 18 and there diffrence is 4

Question

the answer has 2 answers

Answer 1

The sum of two numbers is 18. Let's say these two numbers are a and b. Then sum of a and b is equal to 18

a+b = 18

The difference of these numbers is 4. Then, subtracting b from a should give us 4.

a - b = 4

We have two equations and two unknowns. We can solve these equations. Start with a - b = 4. Write a in terms of b:

a = 4 + b

Now substitute a in the first equation with this value

a + b = 18

(4 + b) + b = 18

4 + 2b = 18 (add -4 to both sides)

2b = 14 (divide both sides by 2)

b = 7

We already now that a = 4 + b. So,

a = 4 + 7 = 11

So, a = 11 and b = 7. Let's check our answer:

Sum of 11 and 7 is 18. CHECK!

Difference of 11 and 7 is 4. CHECK!

Answer 2

Hello Jamya,

If you have two numbers, a & b, that equal a total, c, then you can set an algebra equation to look like

a + b = c

One way to approach this is to start off as a & b to be equal. We know the difference between the two numbers would be d. If we split the difference between the two numbers, you can get

(a+d/2) + (b-d/2) = c

If we start off as a & b being equal, you can divide 18 by 2, and conclude that, to start off, a = b = 9. We already know that c = 18 and d = 4 . Thus

(9+4/2) + (9-4/2) = 18

(9+2) + (9-2) = 18

(11) + (7) = 18

Thus, we can conclude that the two numbers are 11 and 7