in niagra, ny there are 5 male citizens for every 7 female citizens. if the city has a total population of 396 people how many of those people are male

Let's assume number of males 5 * a = 5a

number of females 7 * a = 7a

As per question total population is 396

therefore 5a + 7a = 396

12a = 396

a = 396:12

a = 33

Let's place the value of in the equation

5a + 7a = 396

5*33 + 7*33 = 396

165 + 231 = 396

so 165 of 396 are males