mix something up with something—
1. combine or blend a substance with another substance:
- I mixed the contents up with water and followed the directions on the bottle.
2. mistakenly identify one thing with another:
- They mixed up my name with that of my sister. They then said it was impossible to change the names on the ticket…
mix something with something—
1. = mix something up with something 1:
- Mixing paint with the liquid glue requires a little trial and error, so start with just one color of paint.
2. carry out or consider different activities at the same time:
- Having been badly burned in a previous relationship, Mark never mixes business with pleasure.