Answer: i thought you were telling people what was happening in your home not a question
Step-by-step explanation:
7x + 15 = 1520
It’s $7 times the unknown number of shirts (x). Plus $15 to ship. All has to equal the total of $1,520.
Let the full marks be represented by = x
As given, 80% of x is 75
So,

x= 
x=93.75
Hence, full marks is 93.75
We can check also-
=75