Solve the following system by substitution.

X+2y=14

6x+3y=21

Step-by-step explanation:

x + 2y = 14 ... (1)

6x + 3y = 21 ... (2)

Solve for x in equation 1

When x + 2y = 14

Therefore x = 14 - 2y ... (3)

Now put equation 3 in equation 2 and solve

6x + 3y = 21 ... (2)

6 (14 - 2y) + 3y = 21

Open the bracket and resolve

84 - 12y + 3y = 21

-9y + 84 = 21

Now collect the like terms

-9y + 84 = 21

-9y = 21 - 84

-9y = - 63

Divide through by - 9 to get y

y = - 63/-9

y = 7

Substitute for y in equation (3) to x

x = 14 - 2y ... (3)

So, x = 14 - 2 (7)

x = 14 - 14

x = 0.

Therefore x = 0 and y = 7

Check: From equation (1)

x + 2y = 14

Now, put x = 0 and y = - 2

Therefore, 0 + 2 (7) = 14

0 + 14 = 14