Ann: 21
Jim: 31
Miguel: 63
Let’s start by finding Ann’s number.
a + (a + 10) + 3a = 115
5a + 10 = 115
5a = 115 - 10
5a = 105
a = 105 / 5
a = 21
Now, just find the others’ numbers using Ann’s.
Jim sent ten more messages than Ann, and 21 + 10 = 31.
Miguel sent 3 times as many messages as Ann, and 21 * 3 = 63.
