Answer:

Step-by-step explanation:
Given: Trey's test score average decreased by 14 points this semester.
To find: a signed number to represent this change in average.
Solution:
The decrease can be denoted by minus
sign and increase can be denoted by plus
sign.
So, a signed number to represent the change in test score average is 
=<span><span><span><span><span>16<span>x4</span></span>+<span>40<span>x3</span></span></span>+<span>5<span>x2</span></span></span>−<span>25x</span></span>−<span>6</span></span>
Teachers / Students = 3 / 74
Teachers / 2,500 = 3 / 74
To solve a proportion,
you cross-multiply: Teachers x 74 = 2,500 x 3
Divide each side by 74 : Teachers = 2,500 x 3 / 74
= 101.4 ===> 101 teachers