1.The total expenses($E) of running a birthday party is partly constant and partly varies directly as the number of guests(N) in the party.When N=30,E=1500;when N=40,E=1850.
a)express E in terms of N
b)if 50 guests come to the party,what is the average expense per guest?
c)if the average expense per guest is $40,how many guest come to the party?
2.if (2a-b):(a+b) =2:3,then find a : b
3.let x : y =2 : 1 and y : z=3 : 2,find the value of (x-z)/(2z-y)