Explain how you can determine that (15)(5)=75

Steps to solve:

(15)(5) = 75

~Multiply

15*5 = 75

~Simplify

75 = 75

Therefore, the expression is true.

Best of Luck!

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.