There are some coloured rubber bands in a box. 1/3 of them are blue, 1/4 of them are red and 5/6 of the remainder are yellow.
There are 20 yellow rubber bands. Find the total number of
rubber bands in the box.​

actually your concept is wrong

step-by-step explanation:

150% of x =300

150x=300×100

x=(300×100)÷150

x=200

are ya tryin to ask something or is this a statement

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.