Question

solve the system by substitution.
$y = 6x$
$y = 3x + 21$

Explanation:

Step1: Substitute $y=6x$ into second equation

$6x = 3x + 21$

Step2: Isolate $x$ term

$6x - 3x = 21$
$3x = 21$

Step3: Solve for $x$

$x = \frac{21}{3} = 7$

Step4: Solve for $y$ using $x=7$

$y = 6\times7 = 42$

Answer:

$x=7$, $y=42$