I'm completely lost with this math problem: A group of friends walked into Juju’s Juice Bar ordered a glass of fruit juice each. They spent a total of $94. Some of them ordered mango juice, which sells for $5 a glass, while others asked for pineapple juice, at $6 a glass. If $54 was spent on pineapple juice, how many people were in the group?
Can you give me a hand?