what adds to 18 and subtracts to 8

Question

what two numbers add to 18 and subtract to 8

Answer 1

Add all numbers that make 18 ,then use mental math to subtract those numbers to see if they = 8 then you will get your answer. :)

1+17 17-1 NO

2+16 16-2= NO

3+15 15-3= NO

4+14

5+13** 5+13= 18 13-5=8 ANswer

6+12

7+11

8+10

9+9

Answer 2

Let the number be x and y

Sum of the numbers = 18

That is , x + y = 18 ------- ( 1 )

Difference of the two number = 18

That is , x - y = 8

=> x = 8 + y ---------- ( 2 )

Substitute ( 2 ) in ( 1 ) :

x + y = 18

( 8 + y ) + y = 18

2y + 8 = 18

2y + 8 - 8 = 18 - 8

2y = 10

y = 5

Substitute y = 5 in ( 1 ) or ( 2 ) :

x + y = 18

x + 5 = 18

x + 5 - 5 = 18 - 5

x = 13

[ or in ( 2 ) : x - y = 8

x - 5 = 8

x - 5 + 5 = 8 + 5

x = 13 ]

Therefore, the numbers are 13 and 5