X:y= 5:3 and x+y =56 workout the value of x-y

I only got 2/3 marks for:x + y = 56 (1)
x:y = 5:3
x/y = 5/3
3 x = 5 y
so, x = (5/3)y(2)
sub (2) in (1)
x + y = 56
(5/3)y + y = 56
5 y + 3 y = 168
8 y = 168
y = 168 / 8 = 21
x = (5/3) x 21
= 35
the value of x - y = 35 - 21
= 14
Please help

Janet is mixing a 15% glucose solution with a 35% glucose solution. this mixture produces 35 liters of a 19% glucose solution. how many liters of the 15% solution is januet using in the mixture? a. 25 liters c. 28 liters b. 7 liters d. 10 liters

17 in long 1.3 ft wide and 8in high what is the volume

Bella want to know what the students at her school think of her show. which is the best group to survey to find this information a. go to the mall and ask all of the students she recognizes from school b. ask her viewers to call in durning an episode of the show c. get a list of students at her school from the office and use a random number generator to pick 30 of them d. get a list of students at her school from the office and pick the first 30 students on the list