Steps
So firstly, cross-multiply the proportion:
[tex]3x*21=7*8\\63x=56[/tex]
Next, divide both sides by 63:
[tex]x=\frac{56}{63}[/tex]
Next, we need to simplify the fraction. To do this, we need to divide both the numerator and the denominator by their GCF, or greatest common factor. In this case, their GCF is 7:
[tex]\frac{56}{63}\div \frac{7}{7}=\frac{8}{9}\\\\x=\frac{8}{9}[/tex]
Answer
In short, x = 8/9
