Answer:
x = 6
y = 3
x + y = 9
Explanation:
(Step 1)
Isolate one of the variables in one of the equations. This will allow you to solve by substitution in the following steps.
2x + 3y = 21 <----- Original equation
3y = -2x + 21 <----- Subtract 2x from both sides
y = (-2/3)x + 7 <----- Divide all terms by 3
(Step 2)
Substitute the new equation into the untouched equation and isolate the "x" variable.
4x + 3y = 33 <----- Original equation
4x + 3((-2/3)x + 7) = 33 <------ Substitute manipulated equation
4x - 2x + 21 = 33 <------ Multiply 3 by terms in parentheses
2x + 21 = 33 <------ Subtract terms with variables
2x = 12 <----- Subtract 21 from both sides
x = 6 <----- Divide both sides by 2
(Step 3)
Plug the value of "x" into one of the equations to find the value of "y".
4x + 3y = 33 <----- Original equation
4(6) + 3y = 33 <----- Plug 6 in for "x"
24 + 3y = 33 <----- Multiply
3y = 9 <----- Subtract 24 from both sides
y = 3 <----- Divide both sides by 3
(Step 4)
Since you now know the value of both variables, you can add them together to find your final answer.
x = 6
y = 3
x + y = ?
6 + 3 = ?
9 = ?