On Saturday afternoon, Armand sent m text messages each hour for 5 hours, and Tyrone sent p text messages each hour for 4 hours. Which of the following represents the total number of messages sent by Armand and Tyrone on Saturday afternoon?

(A) |
9mp |

(B) |
20mp |

(C) |
5 +4 mp |

(D) |
4 +5 mp |

Choice C is correct. The total number of text messages sent by Armand can be found by multiplying his rate of texting, in number of text messages sent per hour, by the total number of hours he spent sending them; that is P texts/hour × 5 hours = 5P texts. Similarly, the total number of text messages sent by Tyrone is his hourly rate of texting multiplied by the 4 hours he spent texting: S texts/hour × 4 hours = 4S texts. The total number of text messages sent by Armand and Tyrone is the sum of the total number of messages sent by Armand and the total number of messages sent by Tyrone: 5P + 4S. Choice A is incorrect and arises from adding the coefficients and multiplying the variables of 5P and 4S. Choice B is incorrect and is the result of multiplying 5P and 4S. The total number of messages sent by Armand and Tyrone should be the sum of 5P and 4S, not the product of these terms. Choice D is incorrect because it multiplies Armand’s number of hours spent texting by Tyrone’s hourly rate of texting, and vice versa. This mix-up results in an expression that does not equal the total number of messages sent by Armand and Tyrone.