x = 5.5 % (rounded to nearest tenth) is the change in number of students from last year .
<h3>What is percentage ?</h3>
In mathematics, a percentage is a number or ratio spoken as a fraction of 100. It is often indicated by the percent sign '%', but the abbreviations 'pct.', 'pct', and 'pc' are also sometimes used. Percentages are dimensionless numbers. No units of measure
<h3>Calculation</h3>
825 + 8.25x = 870
8.25x = 870 - 825
x = 45/8.25
x = 5.454545454545455 %
x = 5.5 % (rounded to nearest tenth)
learn more about percentage here :
brainly.com/question/28269290
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