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: company x provides bottled water to its employees in 5 liter bottles , $ 2 each . at least how many 5 l bottles must company x buy monthly , so that new contract with $ 100 fixed monthly rate and $ 1 for 10 l bottle each paid off ? ( assume that no other costs apply ) 
Options: a ) 121 , b ) 125 , c ) 132 , d ) 134 , e ) 138
d

Problem: 5357 x 51 = ? 
Options: a ) 273232 , b ) 273243 , c ) 273247 , d ) 273250 , e ) 273207
e

Problem: find the value of x , y by solving the below equations x + y = 15 x - y = 5 
Options: a ) 10 , 5 , b ) 8 , 7 , c ) 9 , 6 , d ) 11 , 4 , e ) 12 , 3

a