Donna had $9 in her bank account. She made $16 when she mowed her neighbors' lawns. Then, she spent $27 at the movies. How much is left in Donna's bank account?
$-2
$-20
$16
$52

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