In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: village x has a population of 76000 , which is decreasing at the rate of 1200 per year . village y has a population of 42000 , which is increasing at the rate of 800 per year . in how many years will the population of the two villages be equal ? 
Options: a ) 15 , b ) 17 , c ) 11 , d ) 18 , e ) 13
b

Problem: a confectioner decides to sell all of his pastry due to the coming holiday . his pastry goods are equally divided among a group of 28 regular customers . if only 49 customers come to the bakery , each one will receive 6 less pastry goods . how much pastry does the confectioner needs to sell ? 
Options: a ) 392 , b ) 412 . , c ) 432 . , d ) 502 , e ) 522
a

Problem: a certain number when divided by 39 leaves a remainder 20 , what is the remainder when the same number is divided by 13 ? 
Options: a ) 7 , b ) 8 , c ) 9 , d ) 0 , e ) 1

a