This is for an assignment and my brain is literally melting, help thanks

On a piece of paper graph f(x)=5•(0.4)^x

Factor -8x3-2x2-12x-3 by grouping what is the resulting expression?

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!