Answer:
The answer is " red cups is "5.25""
Step-by-step explanation:
Given:
red paint= 
yellow paint= 
total cups=12
i) The Ratio of red and yellow is= 3.5 : 4.5
If the red cups are= 
number of red cups:

ii)

put the value of x in equation (a):

iii)
if
yellow cups used in making orange paint
so, red paint +yellow paint = total cups
let, red paint cups =x
⇒x+6.75=12
⇒x=12-6.75
⇒x=5.25
The value of red cups is 5.25.