Simultaneous equation 3x+y=8, x-3y=11

Answer: x = 3.5 and y = - 2.5

Step-by-step explanation: The pair of simultaneous equations are given as

3x + y = 8 - - - (1)

x - 3y = 11 - - - (2)

From equation (2) make x the subject of the equation

x = 11 + 3y

Substitute for the value of x into equation (1)

3 (11 + 3y) + y = 8

33 + 9y + y = 8

We collect like terms and we now have

33 - 8 = - 10y

25 = - 10y

Divide both sides of the equation by - 10

-2.5 = y

Having solved for the value of y, we now substitute for y into equation (2)

x - 3y = 11

x - 3 (-2.5) = 11

x + 7.5 = 11

x = 11 - 7.5

x = 3.5

Therefore x = 3.5 and y = - 2.5

X=18.5, Y=-2.5

Step-by-step explanation:

Using substitution method

3x+y=8 ... (equation 1)

x-3y=11 ... (equation 2)

Making x in equation 2 has subject of the formula

x=11+3y

Substitute x in equation one

3 (11+3y) + y=8

33+10y=8

10y=8-33

10y=-25

y=-25/10

y=-2.5

Substitute y in equation 2

x-3 (-2.5) = 11

X-7.5=11

x=11+7.5

x=18.5