How to get AVG value by pivot fields

I have some problem, I don't understand how to count AVG value when get all value from model. I have 2 model's. First it's AdminProduct - hold base info about product. Second model it's - PartnerOffer - hold partners offers for AdminProduct. And i have pivot table partner_offer_admin_product - hold 2 foreign keys for table & field price.

AdminProduct.php

public function partnerOffers()
{
   return $this->belongsToMany(PartnerOffer::class, 'partner_offer_admin_product')->withPivot('price);
}

PartnerOffer.php

public function adminProducts()
{
  return $this->belongsToMany(AdminProduct::class, 'partner_offer_admin_product')->withPivot('price);
}

Migration partner_offer_admin_product.php

Schema::create('partner_offer_admin_product', function (Blueprint $table) {
            $table->unsignedBigInteger('admin_product_id');
            $table->unsignedBigInteger('partner_offer_id');

            $table->unsignedDecimal('price', 10, 2);

            $table->foreign('admin_product_id')->references('id')->on('admin_products')->onDelete('cascade');
            $table->foreign('partner_offer_id')->references('id')->on('partner_offers')->onDelete('cascade');
        });

AdminProductRepository.php

public function getAll()
{
$products = AdminProduct::all();
// How to count avg value via pivot table field `price`
}

// How count Avg by id AdminProduct best. Below my solution.
public function getOffers($id)
    {
        $avg = DB::select('select avg(`price`) as value from `partner_offer_admin_product` where `admin_product_id` ='.$id);
        // dd ($avg);

        $collection = collect([
            'item' => [
                'product' => AdminProduct::with('partnerOffers')->find($id),
                'avg_price' => $avg
            ]
        ]);

        return $collection;
        // return $data;
    }

I expect the output object holds list partner offers with AVG all value price for every AdminProduct's

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