This can be solved algebraically. Before we start, as context, to find a percentage you multiply by the percentage/100.
[tex]75*x=90 \\ x= \frac{90}{75} \\ \\ \boxed{x=1.2}[/tex]
This tells us that 90 is 120% of 75. However, your question wants us to find the increase, therefore we don't need that 100.
Therefore, the increase is 20%.
