I will do the first one only. The second question is done the same way.
Replace every x you see in the function with 2b and do the math.
f(x) = x^2 + 2x + 1
Let x = 2b
f(2b) = (2b)^2 + 2(2b) + 1
f(2b) = 4b^2 + 4b + 1
Did you follow? That's all there is to it.
We need to find an equation for each situation. Let x be the number of GB of data used.
Statement 1: At Noise Pollution Cellular, plan A is $30.00 per month and $5.00 for every gigabyte of data used.
Plan A cost equation 
Statement 2: At Noise Pollution Cellular, Plan B is $50.00 per month and $2.00 for every gigabyte of data used.
Plan B cost equation 
Number of GB of data for which both the plan A and plan B cost are <em><u>same</u></em>.

When

When

it is a arithmetic sequence
125 x 1.35= $168.75
168.75 + (168.75 x 0.075)= $181.41
Formula: l•w•h
Answer: 330 yd
Hope that helps :)