1% of 720 = 720/81 = 40 then 81% of 720 = 40 * 81 = 3240

After adding 84 number become 107% so we can write: x + 84 = 107%. we assume initially x will be 100% just after adding 84 it's become 107% means 84 is 7% of x 🧑. so 1 % will be 84/7 =12 we assume x is 100% and value of 100% will be, 1% * 100 = 12 * 100 = 1200

assume initially x was 100% after increasing 20% now it'll be 120% and their value become 66. 40% will 66/3 = 22 (as 120% is 3 time larges than 40) and 20% will be just half of 40%, 40%/2 = 22/2 = 11 (divide by 2 on both side) so, actual value will be, 120% of x is 66; 100% of x will be = 66 - 20% = 66 - 11 = 55;