if { x } is the product of all even integers from 1 to x inclusive , what is the greatest prime factor of { 12 } + { 10 } ?
"soln : { 12 } + { 10 } = 12 * { 10 } + { 10 } = 13 * { 10 } answer : c"
add(divide(add(12, 10), const_2), multiply(1, const_2))