Aight let's answer this step by step
What you need to know is if two values are equal either one will be similar to the other it's only the format that's different if you calculate each of the fractions you'll see each pair is equal except for the last option
Where if calculated
8/3=2.67 but
5/4.8=1.04
Therefore values aren't equal to each other
angle EPF = angle DPG
=> 4x + 48deg = 7x
=> 3x = 48 deg
=> x = 16
=> angle EPF = 4(16) +48 = 112deg
I'm assuming you're talking about the indefinite integral

and that your question is whether the substitution

would work. Well, let's check it out:



which essentially brings us to back to where we started. (The substitution only served to remove the scale factor in the exponent.)
What if we tried

next? Then

, giving

Next you may be tempted to try to integrate this by parts, but that will get you nowhere.
So how to deal with this integral? The answer lies in what's called the "error function" defined as

By the fundamental theorem of calculus, taking the derivative of both sides yields

and so the antiderivative would be

The takeaway here is that a new function (i.e. not some combination of simpler functions like regular exponential, logarithmic, periodic, or polynomial functions) is needed to capture the antiderivative.
if x^2=40 you would need to square root both sides to get x alone therefore x=6.3