Final answer:
Marcos spent $24 on lunches this week.
Step-by-step explanation:
To find out how much money Marcos spent on lunches this week, we need to set up an equation based on the given information. Let d be the amount Marcos spent on lunches. Adelyn spent $3 less than Marcos, so Adelyn spent (d - 3) dollars on lunches. Together, they spent $45 on lunches, so we can write the equation: d + (d - 3) = 45. Simplifying this equation, we get: 2d - 3 = 45. Adding 3 to both sides, we get: 2d = 48. Finally, dividing both sides by 2, we find that d = 24.
Therefore, Marcos spent $24 on lunches this week.