SATMathematics Practice Test 1

The total number of messages sent by Armand is the 5 hours he spent texting multiplied by his rate of texting: m texts/hours × 5 hours=5m texts
Similarly, the total number of messages sent by Tyrone is the 4 hours he spent texting multiplied by his rate of texting: p texts/hours × 4 hours=4p texts.
The total number of 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: 5m+4p.
Choice A is incorrect and arises from adding the coefficients and multiplying the variables of 5m and 4p.
Choice B is incorrect and is the result of multiplying 5m and 4p.
The total number of messages sent by Armand and Tyrone should be the sum of 5m and 4p, not the product of these terms.
Choice D is incorrect because it multiplies Armand’s number of hours spent texting by Tyrone’s 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.