Solution P contains three liquids A, B, and C in the ratio 2:3:5 respectively. Another solution Q contains A, B, and C in the ratio 5:3:2 respectively. Solutions P and Q are mixed in the ratio 7:3 to obtain another solution R. Now 50% volume of R is replaced with another solution having A and B in the ratio 7:3. The resulting solution is Z. Find the percentage amount of B in solution Z.