Add: 5 (0.5k-1)+2 (0.4-k). Answer should be in decimal form

To solve this expression, we can distribute the multiplication:

5(0.5k-1) + 2(0.4-k)
= 2.5k - 5 + 0.8 - 2k

Next, combine like terms:

= 2.5k - 2k - 5 + 0.8
= 0.5k - 4.2

The final answer in decimal form is 0.5k - 4.2.