Answer:
4
Step-by-step explanation:
We are given the following equivalent fractions:
[tex]\dfrac{3}{?} = \dfrac{9}{12}[/tex]
We can reduce the fraction [tex]\dfrac{9}{12} \:\text{by dividing both numerator and denominator by 3}\\\\\dfrac{9\div 3}{12 \div 3} = \dfrac{3}{4}[/tex]
So the missing number, the denominator on the left is 4
