Justin sent 18 messages
Maya sent 26 messages
Dave sent 72 messages
Step-by-step explanation:
Total messages of Maya, Justin and Dave = 116
Maya = 8 + Justin
Dave = 4 * justin = 4justin
Maya + Justin + Dave = 116
8 + Justin + Justin + 4(Justin) = 116
8 + 2(Justin) + 4(Justin) = 116
8 + 6(Justin) = 116
6(Justin) = 116 - 8
6(Justin) = 108
Maya = 8 + Justin = 8 + 18 = 26
Dave = 4justin = 4(18) = 72
Justin sent 18 messages
Maya sent 26 messages
Dave sent 72 messages