Answer :
The number of red balls Luke has at the start is 47.
blue ball per day = 2
red ball per day = -3 ('-' ve sign as he is loosing them)
let the number of red balls be represented by r
let the number of blue balls be represented by b
after 5 days
b+ 10 = r -15 -(i)
After 9 days
b + 18 =2(r-27)-(ii)
subtracting (i) from (ii)
b + 18 - b - 10 = 2r - r - 54 +15
8 = r - 39
r = 39 + 8
r = 47
The number of red balls Luke has at the start is 47
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