Dr. Potter provides vaccinations against polio and measles. Each polio vaccination consists of 4 doses, and each measles vaccination consists of 2 doses. Last year, Dr. Potter gave a total of 60 vaccinations that consisted of a total of 184 doses.
x - number of polio vaccinations y - number of measles vaccinations: x + y = 60 / * ( - 2 ) 4 x + 2 y = 184 -------------------------- - 2 x - 2 y = - 120 + 4 x + 2 y = 184 -------------------------- 2 x = 64 x = 64 : 2 x = 32 32 + y = 60 y = 60 - 32 y = 28 Answer: There were 32 polio and 28 measles vaccinations.
