6^1.2 × 36^? × 30^2.4 × 25^1.3 = 30^5

Answer: Option B

$$\begin{array}{rl}& \text{Let }{6}^{1.2}\times 36^x\times 30^{2.4}\times 25^{1.3}=30^5\\ & \text{Then,}{6}^{1.2}\times (6^2{)}^x\times (6\times 5{)}^{2.4}\times (5^2{)}^{1.3}=30^5\\ & \iff 6^{1.2}\times 6^{2x}\times 6^{2.4}\times 5^{2.4}\times 5^{2.6}=(6\times 5{)}^5\\ & \iff 6^{\left(1.2+2x+2.4\right)}\times 5^{\left(2.4+2.6\right)}=6^5\times 5^5\\ & \iff 6^{\left(3.6+2x\right)}\times 5^5=6^5\times 5^5\\ & \iff 3.6+2x=5\\ & \iff 2x=1.4\\ & \iff x=0.7\end{array}$$