How do I calculate $$\frac{1}{{\frac{1}{7 \times 10^7}- \frac{8\times10^{17}\times 3.1\times 10^7}{6.7 \times 10^{-11}\times \left(1.9 \times 10^{27}\right)^2} }}\tag{1}$$
I put it into Wolfram Alpha and it simply returns the value $7\times 10^7$
Remark: I am new here and this is my first question since this stack exchange site is called 'Mathematica and Wolfram Language' I assumed questions about Wolfram Alpha were allowed. If it turns out that this stack exchange site is only for Mathematica then I have that downloaded also, but I am a complete beginner so I'm not sure which command gives arbitrary precision.
Could someone please explain how to get a precise value of $(1)$ with Mathematica?