80% is the same as 4/5, so 4/5 of the class= 20. That means that if there was a picture, 4 parts would be shaded, and 1 would not. 1/4 of 20 is 5, so 1 part= 5 people. 5 x 5 = 25. 25 is the answer. :)
The answer would be 34/100 or 17/50 if reduced .
X(x+18) <= 175
<span>x^2+18x-175 <= 0 </span>
<span>(x+25)(x-7) <= 0 </span>
<span>So, -25 <= x <= 7 </span>
<span>Or, for real-world tables, </span>
