Answer: The value of x is 28.
Step-by-step explanation:
Since line m is parallel to line l.
So, we assume that
(3x+21)° and (4x-7)° are corresponding angles.
And we know that , corresponding angles formed when a transversal cut the parallel line are equal.
So, they must be equal to each other.
[tex]3x+21=4x-7\\\\21+7=4x-3x\\\\28^\circ=x[/tex]
Hence, the value of x is 28.
