This is about math vocabulary.
When two numbers are added together, the result is called a sum. The two numbers themselves can be called addends, or just "two numbers", or "a number and <something else>". The addition is indicated using a plus sign (+), so the expression "a + b" can be described as "the sum of a and b".
Likewise, when two numbers are multiplied, the result is called a product. As with addition, the two numbers themselves can be called a multiplier and a multiplicand, or just "two numbers" or "a number and <something else>". The multiplication is indicated using any of several symbols (or none at all), including an asterisk (*), a raised dot (·), or an x (×). We try to avoid using the text character "x" to indicate multiplication because it is too easily confused with the variable "x" that is a part of many algebraic expressions. We can say that "a×b" is "a times b", or "the product of a and b."
When a value is added to another, we can say the either is increased by the other. For example, "a+3" can be described as "a increased by 3". We can also describe this as "3 more than a". When subraction is involved instead of addition, the words become "decreased by" or "less than". The meaning is consistent with common English definitions of these words.
The quotient of a and b means "a divided by b."
Then Problem 4 is ...
a) the sum of a number x and 8.1
b) the sum of 10 times a number x and 9
c) the quotient of n and 3
d) 1 less than the product of 5 and x.
