The part of Mateo's goal that is missing in regards to buying the guitar in two months is the amount that is saved towards the goal.
The scenario painted talks about the amount that Mateo earns per week which is $500. Earning this amount, he should be able to purchase the guitar in 5 weeks if he devotes it all to the guitar.
He however says he can only buy the guitar in two months which means that the entire amount is not going towards the guitar. The missing detail is the amount that is saved every week.
Find out more on saving at https://brainly.com/question/341992.