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'.

[EX Q]: Problem: a club wants to mix 20 pounds of candy worth $ 8.00 per pound with candy worth $ 5.00 per pound to reduce the cost of the mixture to $ 6.00 per pound . how many pounds of the $ 5.00 per pound candy should be used ?
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60
[EX A]: c

[EX Q]: Problem: a parking garage rents parking spaces for $ 10 per week or $ 25 per month . how much does a person save in a year by renting by the month rather than by the week ?
Options: a ) $ 120 , b ) $ 160 , c ) $ 220 , d ) $ 240 , e ) $ 260
[EX A]: a

[EX Q]: Problem: if a * a is called a + a , a / a is called a * a , a - a is called a / a , a + a is called a - a . 120 / 40 a " 30 * 20 - 5 = ?
Options: a ) 178.5 , b ) 156.6 , c ) 160.4 , d ) 163.6 , e ) 164.1
[EX A]:
d