what is the Ceofficient of x^4 in the Expansion of (1+X)(1-x) and for what values of the integers n will the term involving x^4 be abscent ​

Can someone me with this problem . show your work .

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line?

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax