Answer:
90 g of water should be added and he will make 900 g of solution.
Step-by-step explanation:
Let x g be the amount of salt Ilya add to 810g of water to make 10% solution. Then 810+x g is the amount of new solution. Thus,
810+x - 100%,
x - 10%.
Mathematically,

So 90 g of water should be added and he will make 810+90=900 g of solution.
Answer:
Step-by-step explanation:
Prime factorization requires dividing by primes starting with smallest prime number
402/2=201
201/3=67, 67 is prime so we cannot go further so the prime factorization of 402 is
2X3X67
2x^3-42x-40=0
2x^3-42x=40
2x(x^2-21)=40
a. 2x=40=>x=20
b. x^2=21+40=>x^2=61=>x=+-(radical(61)