The percent error is 25 %
<em><u>Solution:</u></em>
Given that it is estimated that there are 50 students in the seventh grade class, but there are actually 40
<em><u>To find: percent error</u></em>
Percent error is the difference between a measured and known value, divided by the known value, multiplied by 100%
<em><u>The formula for percent error is given as:</u></em>

Here, exact value = 40 and approximate value or estimated value = 50
Substituting the values in above formula,

Thus the percent error is 25 %
80 1.5 because 10 times 8 equals 80 plus 1.5 equals 80.1.5
1/9 - 5/6
Convert both of them into denominators of 18.
2/18 - 15/18
Subtract the numerators and keep the denominator:
-13/18