1. solve 2 [x + 11-1 = 11 for x.
a x=-5 or x = 6
b x=-5 or x = 7 l
c x=-6 or x = 5
d x=-7 or x = 5

arrange the equations with like terms in columns.

analyze the coefficients of x or y.

add the equations and solve for the remaining variable.

substitute the value into either equation and solve.

check the solution.

step-by-step explanation:

1. perpendicular

2. parallel

3. perpendicular

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 correct answer would be c