What is the value of the expression below when z=4z=4? 3z^2 -10z-5 3z 2 −10z−5

part a: 1.08

part b: 27.59

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.

the easiest way to do these would be to solve the equations. if you can solve the equation than you can solve these problems.