Get the speaker loads correctly sorted out, and nobody needs to buy anything. Do your examination / testing / re-connecting when no-one from the studio is there, so that they don't know how easy it was to sort out. TLSguy has posted everything you need to know. If you don't understand what he posted, get someone else who does to solve this.
If you do, either do them a huge favour and do it Pro Bono, or get greedy and charge them lots of money for what should be about one hour of your time, including loading and unloading the ladder, if you need it.
Dance Studios don't need "High Fidelity" sound systems; they're not thinking about the tone of the clarinets. It's just beats or instruction. I'd wager that half the Dance Studios in America use a $50 blaster sitting on a window sill. Easy peasy stuff, an Airport intercom can pull it off (almost).