A retail clothing store offers customers an opportunity to open a credit card during checkout. One location of the retail clothing store states that the number of credit cards, [tex]A[/tex], that are opened [tex]t[/tex] months since January can be modeled by the function [tex]A(t) = 10 + 2t[/tex]. The number of credit cards opened at another location, [tex]B[/tex], is defined by the function [tex]B(t) = 25 - t[/tex]. What is an expression that can be used to determine the total amount of credit cards opened at the two locations?

A. [tex](A + B)(t) = 35 + t[/tex]

B. [tex](A + B)(t) = 35 + 3t[/tex]

C. [tex](A - B)(t) = -15 + t[/tex]

D. [tex](A - B)(t) = -15 + 3t[/tex]



Answer :

Let's address the problem step-by-step to understand what happens when combining the functions [tex]\(A(t)\)[/tex] and [tex]\(B(t)\)[/tex].

The function for the number of credit cards opened at the first location is given by:
[tex]\[ A(t) = 10 + 2t \][/tex]

The function for the number of credit cards opened at the second location is:
[tex]\[ B(t) = 25 - t \][/tex]

### Combining the Two Functions

To find the total number of credit cards opened at both locations, we need to determine the expression for [tex]\( (A + B)(t) \)[/tex].

1. Sum of the two functions:
[tex]\[ (A + B)(t) = A(t) + B(t) \][/tex]

Substituting in the given functions:
[tex]\[ (A + B)(t) = (10 + 2t) + (25 - t) \][/tex]

2. Simplify the expression:
Combine like terms:
[tex]\[ (A + B)(t) = 10 + 2t + 25 - t \][/tex]
[tex]\[ (A + B)(t) = 35 + t \][/tex]

So, the expression to determine the total number of credit cards opened at the two locations is:
[tex]\[ (A + B)(t) = 35 + t \][/tex]

From the choices given:
- [tex]\((A+B)(t)=35+t\)[/tex] - This is correct.
- [tex]\((A+B)(t)=35+3t\)[/tex] - Incorrect, doesn't match our simplified expression.

### Difference of the Two Functions

To find the expression for the difference in the number of credit cards opened at both locations, we need to determine [tex]\( (A - B)(t) \)[/tex].

1. Difference of the two functions:
[tex]\[ (A - B)(t) = A(t) - B(t) \][/tex]

Substituting in the given functions:
[tex]\[ (A - B)(t) = (10 + 2t) - (25 - t) \][/tex]

2. Simplify the expression:
Distribute the negative sign and combine like terms:
[tex]\[ (A - B)(t) = 10 + 2t - 25 + t \][/tex]
[tex]\[ (A - B)(t) = -15 + 3t \][/tex]

So, the expression for the difference in the number of credit cards opened at the two locations is:
[tex]\[ (A - B)(t) = -15 + 3t \][/tex]

From the choices given:
- [tex]\((A-B)(t)=-15+t\)[/tex] - Incorrect.
- [tex]\((A-B)(t)=-15+3t\)[/tex] - This is correct.

### Summary

The correct expressions based on the given choices are:
[tex]\[ (A + B)(t) = 35 + t \][/tex]
[tex]\[ (A - B)(t) = -15 + 3t \][/tex]