Given system equation
{ ((x^2 +3xy+y^2 +1=0)),((x^3 +y^3 −7=0)) :} has solution
(x_1 ,y_1 ) &(x_2 ,y_2 ) for x,y∈R. Find the value
of x_1 ^2 .y_2 +x_2 ^2 .y_1 .
A and B can do a job in 10 days and 5 days, respectively. They worked together for two days, after which B was replaced by C and the work was finished in the next three days. How long will C alone take to finish 40% of the job?