Answer 1

Let the number to be subtracted from the given polynomial be k 

let` f(y)=3y^3+y^2-22y+15-k `

it is given that f(y) is divisible by` (y+3) `

Remainder=`f(-3) =0 `

`3(-3)^3+(-3)^2-22(-3) +15-k=0 `

`-81+9+66+15-k=0 `

`9-k=0` 

`k=9 `