Respuesta :

[tex]\text{21 + m = 66}[/tex]Explanation:

The sum of 21 and Mabel's score is 66:

This means 21 was added to Mabel's score to give 66

let Mabel's score = m

21 + Mabel's score = 66

In the from equation:

[tex]\text{21 + m = 66}[/tex]