Hey!!
A cell phone company charges $45 a month and hence, this would be constant and would be same the same value. And the company charges $0.25 for every text message.
Let's take the number of text messages as ' t '
The question asks us to find the number of text messages needed to make it $75 for the first month.
We know, the constant is $45 and we know the number of text messages as ' t ' and we also know the cost of each text messages is $0.25. And with all this given, we can find the total cost which is denoted by ' c '.
The total cost would be the price of a month added to the cost of text messages.
The total cost = c
The price of for month = $45
The price of text messages = $0.25t
Now, let's form the equation :
... c = 45 + 0.25t ( this is the equation )
The total cost given is $75
Hence, the equation would be :
... 75 = 45 + 0.25t
Subtract 45 on both sides
... 30 = 0.25t
Divide 0.25 on both sides
... t = 120
Hence, the answer would be option ( D )
Hope my answer helps!!