Answer: It Diego i think please don’t be mad at me if you get it wrong
Mom is 30 years old when Serena is 10 because 10 x 3 = 30.
They are 20 years apart. [This is key]
Half (.5) of mom's age will be = to Serena's age.
Therefore, when mom is 40 years old, Serena is 20 years old.
We can see that half of 40 = 20.
Hope this makes sense!
Um the answer is 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.... Infinity until answer.
Hope this helps brainliest if correct.
can you explain more detailed ? is about exel? or other thing pls i can help you if you explain more detail