multiply and simplify
10b^6/3r^2 x 9r^7/100b
10b^6 /(3r^2*9r^7/100b),
10b^6/(27r^9/100b),
Invert fraction and multiply:
10b^6 * 100b/27r^9,
1000b^7 / 27r^9.
10b^6/3r^2 x 9r^7/100b
10b^6/(27r^9/100b),
Invert fraction and multiply:
10b^6 * 100b/27r^9,
1000b^7 / 27r^9.