If 3/5 of students carry iPhone, what fraction of students is this using 75 as the denominator

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9

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