Help plz. I think the starting number is 100% Buu I don't know.

19%

Step-by-step explanation:

if the starting number is 100 then 100 decreased by 10% is 100 times 0.9 =90

and decrease 10% again is 81 and in total decrease by 19%

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

hope it

2x^2+5x+17

your welcome. : )