为什么会报错

#include<bits/stdc++.h>
using namespace std;
double n,t,v;
struct node{
	double price;
	double m;
}; 
node a[110]; 
bool cmp(node x,node y){
	return x.price>y.price;
}
int main(){
	cin>>n>>t;
	for(int i=1;i<=n;i++){
		cin>>a[i].m>>v;
		a[i].price=v/a[i].m;
	}
	sort(a+1,a+n+1,cmp);
	v=0;
	for(int i=1;i<=n;i++){
		if(t<a[i].m){
			v+=t*a[i].price;
			break;
		}
		t-=a[i].m;
		v+=a[i].m*a[i].price;
	}
	cout<<v;
	return 0;
}

18	13	C:\Users\lenovo\Desktop\未命名1.cpp	[Error] invalid operands of types 'node [110]' and 'double' to binary 'operator+'