Perform algebraic division:
5x+4 (Each multiplier is added into the quotient)
3x²-2x+5 ) 15x³+2x² -3
subtract 15x³-10x²+25x (multiplier 15x³÷3x²=5x)
12x²-25x
subtract 12x²- 8x+20 (multiplier 12x²÷3x²=4)
-17x-23 remainder
So (5x+4)(3x²-2x+5)-17x-23=
15x³-10x²+25x+12x²-8x+20 - 17x-23=
(15x³+2x²+17x+20)-17x-23=15x³+2x²-3.