How would i find the missing side

Lorenzo ate 2/5 of his bag of almonds. his 4 friends ate equal shares of the remaining bag of almonds?

Mr and mrs smith buy tickets for themselves and their four children. the cost of an adult ticket is ? 6 more than the adult ticket. the total cost of the six tickets is ? 40.50 work out the cost of an adult ticket. in your working let c be the cost of the child ticket and a be the cost of the adult ticket.

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?