were asked a factor. This train a meal here. Why score tells us that both factors mustard with why and the negative 20 ones that tells us that it will be a number, Time said. And another number, Time said. And these two numbers must multiply together to be negative 21 and add together to be negative for. So if we list are factors of negative 21 we will get negative one comma, 21 negative, three comma seven Negative seven comma three and they give 21 comma one and out of these pears on Lee the negative seven comma three. Well, multiply. Sorry, we'll add together to be negative for So this tells us that are factors are going to be why minus seven said. And why? Plus three said.