IMC 2002 — Keystage 3 (IWYMIC) — individual Question 4

Let $P(x)=x^4+ax^3+bx^2+cx+d$, where $a,b,c,d$ are constants. If $P(1)=10$, $P(2)=20$, $P(3)=30$, find $P(10)+P(-6)$.