Question

X - 3y y = 5 and x=21

Answer 1

{x,y} = {6,-5}

Explanation:

// Solve equation [2] for the variable x

[2] x = 3y + 21

// Plug this in for variable x in equation [1]

[1] (3y+21) + y = 1

[1] 4y = -20

// Solve equation [1] for the variable y

[1] 4y = - 20

[1] y = - 5

// By now we know this much :

x = 3y+21

y = -5

// Use the y value to solve for x

x = 3(-5)+21 = 6

Solution :

{x,y} = {6,-5}