<span><u>Answer</u>
25c^2-4/9
<u>Explanation</u>
In this question you are expected to expand (5c+2/3)(5c-2/3)
(5c+2/3)(5c-2/3)=(5c×5c)-(5c×2/3)+(5c×2/3)-(2/3×2/3)
=25c^2-10c/3+10c/3-4/9
25c^2-4/9
The expanded form of (5c+2/3)(5c-2/3) is 25c^2-4/9 and this is what the question requires of you to do.</span>
The Z-score is calculated by the formula below

Step 2: Substitute the given parameters in the formula

Hence, the z-score of a person who scored 145 on the exam is -0.5