React problem with implementation (two items to one value)

Im trying to get something like cart, so the values will be counted times quantity, ive "modded" something like this, but this doesnt work:

I will start with the API response:

    "magazyn": [
      {
        "productId": 1,
        "productGUID": "491a8965545a4071bda2811094cf55d1",
        "productSKU": 10,
        "productTitle": "aaaaaa",
        "productCategory": "string",
        "productDescription": "string",
        "productQuantity": 1,
        "productVatRate": 1,
        "productNettoPurchasePrice": 1,
        "productNettoSellingPrice": 1,
        "productNettoSalesMargin": 1,
        "productBruttoSellingPrice": 1,
        "productNettoIncomeValue": 1,
        "productVolume": "Szt"
      },
      {
        "productId": 2,
        "productGUID": "21a63a6a0ff84cb0b1b476284ffe7368",
        "productSKU": 13,
        "productTitle": "absddad",
        "productCategory": "string",
        "productDescription": "string",
        "productQuantity": 2,
        "productVatRate": 2,
        "productNettoPurchasePrice": 2,
        "productNettoSellingPrice": 2,
        "productNettoSalesMargin": 2,
        "productBruttoSellingPrice": 38,
        "productNettoIncomeValue": 2,
        "productVolume": "Szt"
      }
    ],
    "productId": [
      {
        "pcID": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
        "productId": 1,
        "productQuantity": 5
      },
      {
        "pcID": "6b29fc40-ca47-1067-b31d-00dd010662da",
        "productId": 2,
        "productQuantity": 4
      }
    ]

{item.productId.map(val => (
 item.magazyn.map((item2) => item2.productBruttoSellingPrice).reduce((previousValue, currentValue2) => {
return previousValue + currentValue2 * val.productQuantity;
}, 0)
))}

I also tried with

{item.productId.map((val) => val.productQuantity).reduce(firstVal, nextVal) => {
 item.magazyn.map((item2) => item2.productBruttoSellingPrice).reduce((previousValue, currentValue2) => {
return previousValue + currentValue2 * val;
}, 0)
},0)
)}

But the first one gives weird values like, for example when the result is 30 this gives me 3030, the second attempt is gives nothing

my problem is that, the magazyn give me the product price, but the "productId" object gives me a quantity, i want to merge it like when productId.productId == magazyn.productId then productQuantity * productBruttoSellingPrice and this one will be in the loop because we have different items in "productId" object.

Could you try the following? Do I interpret what you are expecting?

const magazyn = [...item.magazyn];
const productId = [...item.productId];

let sum = 0;
magazyn.forEach((value1) => {
  productId.forEach((value2) => {
    if (value1.productId === value2.productId){
        sum= sum + 
value1.productBruttoSellingPrice * 
value2.productQuantity
    } 
  });
});

console.log(sum);