A cement truck is pouring cement for a new 4in. thick driveway. The driveway is 90ft long and 20 ft wide wide. How long will it take the truck to pour the cement if it release 10ft^3 cement per minute?

thus, the first answer choice, y = sec x, is the correct one

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.