In fission, a is one where a neutron imbeds itself in the nucleus of a u-235 atom causing it to break apart. after destructing, more neutrons are created. these neutrons can carry on the cycle by finding more u-235, and, again, starting the fissioning process.

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.

it is a negative acceleration

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form

answer: 31, 5556. 952 seconds