Sounds like 18 servings to me.
6 quarters go into 1.5
6 x 3 is 18 so 18 servings.
I would do the work out but it’s a lot of work so heres a picture the work is already done.
The answer to your question is 4:10
First solve for the slope, m using the two points given. It doesn't matter which point you choose as point 1 or 2 as long as you're consistent.
m = (y2 - y1)/(x2 - x1)
point 1: (–6.4, –2.6)
point 2: (5.2, 9)
m = (9 - -2.6)/(5.2 - -6.4)
m = (9 + 2.6)/(5.2 + 6.4)
m = 11.6/11.6
m = 1
put the newly found slope into the linear equation for m
y = (1)x + b
y = x + b
Now solve for the y-intercept, b
by putting one of the given points
9 = 5.2 + b
b = 9 - 5.2
b = 3.8
final equation:
y = x + 3.8
Answer is 26.31%
The % of red marbles is 26.3157895