How do i solve 512 = k^3 step by step ?

If x + 10 = 70, what is x? a. 40 b. 50 c. 60 d. 70 e. 80

William invested $5000 in an account that earns 3.8% interest, compounded annually. the formula for compound interest is a(t) = p(1 + i)t. how much did william have in the account after 6 years? (apex)

Joline is solving the equation 0=x^2-5x-4 using the quadratic formula which value is the negative real number solution to her quadratic equation round to the nearest tenth if necessary