Question 675054
Let x = Kelly's current age
Matt's current age is 5x+1

Kelly's age in 3 years = x+3
Matt's age in 3 years = 5x+1+3

Matt's age in 3 years = 3 times Kelly's age in 3 years
5x+1+3 = 3(x+3)
5x+4=3x+9
subtract 4 from both sides
5x=3x+5
subtract 3x from both sides
2x=5
divide both sides by 2 to get x by itself
x=2.5

answer:  Kelly is 2.5 years old
Matt is 5(2.5)+1 = 13.5 years old