Respuesta :
------------------------------------------------------------
Define x :
------------------------------------------------------------
Let x be the smaller number.
Let y be the larger number.
------------------------------------------------------------
Construct the equations :
------------------------------------------------------------
Three times the larger number is equal to 4 times the smaller ones.
⇒ 3y = 4x
The sum of the numbers is 21
⇒ x + y = 21
------------------------------------------------------------
Solve for x and y :
------------------------------------------------------------
3y = 4x -------------------- (1)
x + y = 21 ----------------- (2)
------------------------------------------------------------
From equation (2) :
------------------------------------------------------------
x + y = 21
x = 21 - y
------------------------------------------------------------
Substitute x = 21 - y into equation (1) :
------------------------------------------------------------
4y = 3( 21 - y)
4y = 63 - 3y
7y = 63
y = 9
------------------------------------------------------------
Substitute y = 9 into equation 2 :
------------------------------------------------------------
x + y = 21
x + 9 = 21
x = 21 - 9
x = 12
------------------------------------------------------------
Answer : The two numbers are 9 and 12.
------------------------------------------------------------
Define x :
------------------------------------------------------------
Let x be the smaller number.
Let y be the larger number.
------------------------------------------------------------
Construct the equations :
------------------------------------------------------------
Three times the larger number is equal to 4 times the smaller ones.
⇒ 3y = 4x
The sum of the numbers is 21
⇒ x + y = 21
------------------------------------------------------------
Solve for x and y :
------------------------------------------------------------
3y = 4x -------------------- (1)
x + y = 21 ----------------- (2)
------------------------------------------------------------
From equation (2) :
------------------------------------------------------------
x + y = 21
x = 21 - y
------------------------------------------------------------
Substitute x = 21 - y into equation (1) :
------------------------------------------------------------
4y = 3( 21 - y)
4y = 63 - 3y
7y = 63
y = 9
------------------------------------------------------------
Substitute y = 9 into equation 2 :
------------------------------------------------------------
x + y = 21
x + 9 = 21
x = 21 - 9
x = 12
------------------------------------------------------------
Answer : The two numbers are 9 and 12.
------------------------------------------------------------
