Final answer:
The true statements for the expression 623 - 822 + 40y + 21 are: b. There are four terms. To be clear, these terms are 623, -822, +40y, and +21. Options a, c, and d do not represent the expression accurately.
Step-by-step explanation:
When analyzing the expression 623 - 822 + 40y + 21, we're looking to identify some properties of it. First, we should clarify that an expression can have several terms, and each term is separated by a plus (+) or minus (-) sign. Now, let's evaluate the given statements based on this expression:
b. There are four terms. This statement is true. The terms are 623, -822, +40y, and +21.
c. There are three terms. This statement is false because, as stated above, there are four terms.
a. The entire expression is a difference. This statement is false because the expression is not just a difference; it includes the addition of terms as well.
d. The term -40y is a ratio. This is false. The term -40y is not a ratio but rather a product of -40 and the variable y.
Considering this, the true statements are b. There are four terms. and none of the other options given are true for this expression.