80% of what number is 960? Answer pls

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

Eis the midpoint of line segment ac and bd also line segment ed is congruent to ec prove that line segment ae is congruent to line segment be

For what value of (y) is 3^3/3^y =1/9