I found out that I can copy equation from Symbolab or Word 365 and paste it to Blogger with a kind of HTML codes I got from How to convert Latex to mathml.
<!DOCTYPE html>
<html>
<head>
<title>MathJax TeX Test Page</title>
<script type="text/javascript" async
src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_CHTML">
</script>
</head>
<body>
Your test: $${\pi_{ij}}={\rm{R}}SBU_{ij}^L-{\rm{R}}SBU_{ij}^H={q_{ap}}(f_{ij}^L-f_{ij}^H)/{N_{ap}}.$$
</body>
</html>
It converts my Latex to MathML, but I cannot see my equation in Blogger editor if I switch HTML editing mode to usual writing mode. I cannot see where my mathematical equation is when I want to type some paragraphs for my Science Web Novel without getting distracted by HTML codes.