Q:
sean wants to make a mixture that is 50% lemon juice and 50% lime juice.
how much 100% lemon juice should he add to a juice mixture that is 30% lemon juice and 70% lime juice to make 7 gal of the 50% lemon/50% lime juice mixture?
note:
i'm struggling with this problem as i don't know how to go about solving it. could someone me and explain what to do?

 well, if he wants 50% lemon and 50% lime, and there's already 30% lemon and 70% lime, then he would have to add 40% more lemon juice i belive, because he wants it half and half lemon and lime

To get this you would need to subtract 7-3=4, and then add the 0's on the end, 40%, because 70% and (30% + 40%) = both to be 70%, so really it's half and half i believe

sorry if i got this wrong, i'm not very good with these things, but i hope this helped!