a can do a piece of work in 80 days . he works at it for 10 days b alone finishes the remaining work in 42 days . in how much time will a and b working together , finish the work ?
"work done by a in 10 days = ( 1 / 80 * 10 ) = 1 / 8 remaining work = ( 1 - 1 / 8 ) = 7 / 8 now , 7 / 8 work is done by b in 42 days . whole work will be done by b in ( 42 x 8 / 7 ) = 48 days . a ’ s 1 day ' s work = 1 / 80 and b ' s 1 day ' s work = 1 / 48 ( a + b ) ' s 1 day ' s work = ( 1 / 80 + 1 / 48 ) = 8 / 240 = 1 / 30 hence , both will finish the work in 30 days . answer is b ."
inverse(add(divide(const_1, 80), divide(const_1, multiply(42, const_2))))