42= Combined age
x= Sammy's age
3x+2= Mom's age (she is two years more (+2) than three times Sammy's (3x)
Add their ages together to equal 42:
x+(3x+2)=42
4x+2= 42
Subtract 2 from both sides
4x= 40
Divide 4 from both sides
x= 10 Sammy's age
Substitute his age into his Mom's equation above
3x+2= 3(10)+2= 30+2= 32 Mom's age
Check:
Sammy's age + Mom's age = 42
10+32=42
42= 42
Hope this helps! :)