\begin{aligned} \dfrac43&=q+\dfrac13\\\\ \dfrac43-\dfrac13&=q+\dfrac13-\dfrac13&\green{\text{Step } 1}\\\\ \dfrac23&=q&\blue{\text{Step } 2} \end{aligned}
3
4
​

3
4
​
−
3
1
​

3
2
​

​

=q+
3
1
​

=q+
3
1
​
−
3
1
​

=q