Somebody please help meee

Given this information, which expression must represent the value of b?

Cass decided to sell game programs for the hockey game. the printing cost was over 20 cents per program with a selling price of 50 cents each. cass sold all but 50 of the programs, and made a profit of $65. how many programs were printed? letting p represent the number of programs printed, set up an equation that describes this situation. then solve your equation for p.

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)