Answer:
[tex]28[/tex]
Step-by-step explanation:
A dilation we multiply to find what the dilated line will be but, since we need to find the original line then we divide
[tex]21[/tex]÷[tex]\frac{3}{4}[/tex]
Skip flip multiply
[tex]\frac{21}{1} *\frac{4}{3}[/tex]
Multiply
[tex]\frac{84}{3}[/tex]
Simplify
[tex]28[/tex]
I hope this helps
