To find the correct equation that represents the number of measures Harita still needs to memorize after `d` days of practice, let's follow the given scenario step by step.
1. Total Measures:
Harita needs to memorize a total of 90 measures.
2. Memorization Rate:
Harita memorizes 18 measures every 3 days. To find the rate at which she memorizes measures per day, we can calculate:
[tex]\[
\text{Measures per day} = \frac{18 \text{ measures}}{3 \text{ days}} = 6 \text{ measures per day}
\][/tex]
3. Formulating the Equation:
Let [tex]\( d \)[/tex] represent the number of days of practice. After [tex]\( d \)[/tex] days, the number of measures Harita has memorized can be calculated as:
[tex]\[
\text{Measures memorized} = 6d
\][/tex]
4. Remaining Measures:
To determine the number of measures she still needs to memorize ([tex]\( m \)[/tex]), subtract the measures she has already memorized from the total measures:
[tex]\[
m = 90 - 6d
\][/tex]
Therefore, the correct equation that represents the number of measures Harita still needs to memorize after [tex]\( d \)[/tex] days of practice is:
[tex]\[
m = 90 - 6d
\][/tex]
Among the given options, the correct one is:
[tex]\[ m = 90 - 6d \][/tex]
