Question: how do I solve this error in Maple?

a1:=odeplot(p,[t,x(t)],0..5,color=black,thickness=2):

a2:=plot((2/125)*t^3-(3/25)*t^2+t+1,t=0..5,color=red,style=point,thickness=4):
display(a1,a2,labels=[x1,x2]);
Error, (in plots:-display) expecting plot structure but received: a1
 

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