povećati

1. (of amount) to increase; to raise
   Firma je povećala plate za deset odsto. — The company raised salaries by ten percent.
   Vlada je povećala cenu struje. — The government increased the price of electricity.
2. (of size, an image) to enlarge; to magnify; to expand
   Povećaj sliku da bolje vidim. — Zoom in on the picture so I can see better.
   Povećali su dvorište kad su kupili susedni plac. — They expanded the yard when they bought the plot next door.
3. (povećati se) to increase; to grow
   Broj turista se ove godine povećao. — The number of tourists increased this year.

The imperfective is povećavati; 'by how much' is za + acc.: povećati za 10%.