Answer:
Plan A:
C = $80
C = cost
Plan B:
C = 0.15t + 20
C = cost; t = amount of text messages
Explanation:
Let C = cost.
Let t = amount of text messages.
Plan A:
C = $80
Plan B:
C = 0.15t + 20
If the next question asks for you to solve when Plan B will be equal to Plan A, set the two equations equal to each other.
80 = 0.15t + 20
Isolate the variable, t. Note the equal sign, what you do to one side, you do to the other. Do the opposite of PEMDAS.
First, subtract 20 from both sides.
80 (-20) = 0.15t + 20 (-20)
80 - 20 = 0.15t
60 = 0.15t
Divide 0.15 from both sides.
(60)/0.15 = (0.15t)/0.15
60/0.15 = t
t = 400
Those who use Plan B must send at least 400 text message to have the same price as Plan A.
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