In what ratio must tea at Rs.62 per Kg be mixed with tea at Rs. 72 per Kg so that the mixture must be worth Rs. 64.50 per Kg?

Find prt:qsu, given that p:r=2:3, q:s=4:3, r:t=8:9, s:u=3:2 and t:q=3:4

In what ratio must water be mixed with milk costing Rs.12 per litre in order to get a mixture worth of Rs.8 per litre?