Answer :
Answer:
The numbers are: '12' and '9'
Step-by-step explanation:
Let the numbers be 'x' and 'y'
[tex]x+y=21[/tex] Equation:1
[tex]x-y=3[/tex] Equation:2
Finding the value of one variable from a equation and putting it in the other equation:
From equation:2
[tex]x-y=3[/tex]
Adding 'y' both sides:
[tex]x=3+y[/tex] Equation:3
Put the 'x' in Equation:1
[tex]x+y=21[/tex]
[tex](3+y)+y=21[/tex]
Adding the like terms:
[tex]3+2y=21[/tex]
Subtracting '3' both sides:
[tex]2y=21-3\\\\2y=18[/tex]
Dividing by '2' both sides:
[tex]y=18/2\\\\y=9[/tex]
Put the value of 'y' in Equation:3
[tex]x=3+y[/tex]
[tex]x=3+9\\\\x=12[/tex]
The numbers are: '12' and '9'