(l(0.21-0.037)l/0.21)x100
Find |0.21 - 0.037| first; this is |0.173| which is 0.173.
( 0.173 / 0.21) x 100
Do what's inside parenthese first: 0.173 / 0.21 = 0.8238095 (etc)
Then multiply by 100 ---> 82.38095 ...