svetlanas hair is 4 centimeters long her hair grows 1.5 centimeters per month. Svetlana wants her hair to be less than 16 centimeters long.

I guess the question is when her hair will be almost 16cm long.

So she needs to grow hair almost 12 cm of hair. Because 16-4=12

To grow 12cm hair she needs 8 months (12/1.5=8)

So Svetlana needs to cut her hair before 8th month.