De la 2surse coerente aflate la distanta d=2 metri una de alta se propaga intrun mediu elastic unde cu viteza =340 m/s. la distanta L =4 metri de la mijlocul dintre surse perpendicular pe segmentul care le uneste a fost inregistrat un maxim de interferenta iar urmatorul la distanta de 1, 5 metri de la acesta pe linia paralela cu cea pe care se afla sursele. Care este frecventa de oscilatie a surselor?

Explanation:

The text is in Romanian language, however here's a clearer rendering which reads;

"From 2 coherent sources at a distance d = 2 meters from each other, it propagates in an elastic medium where with velocity = 340 m/s. At a distance L = 4 meters from the middle between sources perpendicular to the segment joining them a maximum of interference and the next at a distance of 1.5 meters from it on the line parallel to the one on which the sources are located. What is the frequency of oscillation of the sources?."