Question

harita must memorize 90 measures of music for her cello solo at a concert. she plans on memorizing 18 new measures for every 3 days of practice. which equation can be used to determine m, the number of measures harita still needs to memorize, as a function of d, the number of days of practice since she began learning the piece?
m = 72 - 15d
m = 90 - 6d
m = 101 - 21d
m = 108 - 3d

Explanation:

Step1: Find the daily memorization rate

Harita memorizes 18 measures in 3 days. So the daily rate is $\frac{18}{3} = 6$ measures per day.

Step2: Determine the equation structure

The total measures to memorize is 90. The number of measures memorized after $d$ days is $6d$. So the number of measures still needed $m$ is total minus memorized: $m = 90 - 6d$.

Answer:

$m = 90 - 6d$ (the second option)