Denis bought 50 postage stamps for which she paid $13.00. Some were 20-cent stamps and some were-40 cent stamps. How many of each did she buy? (Please show work with Substitution or Elimination Method)

Asales representative from a local radio station is trying to convince the owner of a small fitness club to advertise on her station. the representative says that if the owner begins advertising on the station today, the club's total number of members will grow exponentially each month. she uses the given expression to model the number of club members, in hundreds, after advertising for t months.

Prove that 16^4-2^13-4^5 is divisible by 11.

Vinny is interviewing for a job.he wants his take home pay to be at least $42,000.what is the least salary he can earn if he pays 25% income tax?