To get how many customers Sam has, write an equation that will relate to the gross profit. Let n be the customers. Since for 52 weeks, Sam charges $25 per week per person, multiply n by the number of weeks and the charge. The equation is written as $88,400 = 52 weeks x $25 per week x n persons. Divide $88,400 by the product of 52 weeks and the $25 charge. The answer will be 68. The annual operating expense $48,000 is just there to make confusion.
Let's go through this problem step by step while bearing in mind the concept of
PEMDAS.
Step 1:

Declaration of the expression. Nothing wrong here yet.
Step 2:

Clarise evaluated what's inside the parenthesis first - which was the right thing to do! There are no mistakes in this step.
Step 3:

In this step she subtracted first. This should not be the case! PEMDAS tells us that the exponents and division gets higher priority than subtraction. This is therefore the first mistake Clarise makes.
Step 4:

In this step Clarise evaluates the exponent. This does not violate any rules (relative to the previous expression) since PEMDAS tells us that exponents take higher priority than division.
Step 5:

(Clarise's final answer)
In Clarise's final step, she manages to get the wrong answer! Dividing 51.68 by 0.16 would give us 323. This is another mistake of Clarise.
Looking at the choices, we can now identify what mistakes Clarise made:
-She subtracted before evaluating the exponents
-She subtracted before she divided
-She divided incorrectly
<span> here
7 7/8
= [ (8*7) + 7 ] / 8
= (56 + 7) / 8
=63 / 8
similarly,
3 1/4
=[ (4*3) + 1] / 4
= (12 + 1) / 4
= 13/4
----------------------------
now put the values
7 7/8 - 3 1/4
= 63/8 - 13/4
here, take LCM of 8 & 4 which is 8.
now,
[ (1*63) - (2 * 13) ] / 8
= (63 - 26) / 8
= 37/8
= 4 5/8........................[ here, divide 37 by 8 which gives reminder as 5 and divisible value as 4 ]</span>