Question

The value of two numbers if their sum is 21 and their difference is 3

Answer 1

Answer:

The numbers are:   '12' and '9'

Step-by-step explanation:

Let the numbers be 'x' and 'y'

$x+y=21$    Equation:1

$x-y=3$      Equation:2

Finding the value of one variable from a equation and putting it in the other equation:

From equation:2

$x-y=3$

Adding 'y' both sides:

$x=3+y$      Equation:3

Put the 'x' in Equation:1

$x+y=21$

$(3+y)+y=21$

Adding the like terms:

$3+2y=21$

Subtracting '3' both sides:

$2y=21-3\\\\2y=18$

Dividing by '2' both sides:

$y=18/2\\\\y=9$

Put the value of 'y' in Equation:3

$x=3+y$

$x=3+9\\\\x=12$

The numbers are:   '12' and '9'

Answer 2

Answer:

9 and 12

Step-by-step explanation: