Question

4x - y = 7\
y = 3x

Explanation:

Step1: Substitute $y=3x$ into first equation

$4x - 3x = 7$

Step2: Simplify to solve for $x$

$x = 7$

Step3: Substitute $x=7$ into $y=3x$

$y = 3\times7$

Answer:

$x=7$, $y=21$