b
A
\(5^{3x-2}:5^{2x-1}=125\)
\(3x-2-2x-1=3\)
\(=>x=2\)
hoang mạc xa-ha-ra
\(3^{x+1}=3^{17}\)
\(=>x+1=17\)
\(=>x=16\)
C
16x5x(80%-20%)=90x\(\dfrac{80}{100}=72\)