Initially, there is 450kg of solution containing 75% water and 25% salt in the tank. At any given moment, a salt solution of 35% by weight started to be fed into the tank at a rate of 12kg/min. The rate of the output current is 10kg/min. Calculate the salt content in the tank after 20 minutes using the Euler method. Take t=4 min

Xn+1=Xn +(dX/dt)nt

tn+1 =tn +t