Answer:
Zuri: -10x + 125, Cara: 10x+125, Julio: 125x + 10
Explanation:
Zuri starts with 125 dollars, and spending 10 dollars per month, means a subtraction of $10 per month. So, after x months, the subtraction = -10x = -10 + -10 + ... + -10, x times. Thus, f(x) = 125 + (- 10x) = 125 - 10x = -10x + 125.
Cara starts with 125 coins, and collecting 10 coins per year, means an addition of 10 coins per year. So, after x years, the addition = 10x = 10 + 10 + ... + 10, x times. Thus, f(x) = 125 + 10x = 10x + 125.
Julio starts with $10, and earning $125 per week, means an addition of $125 per week. So, after x weeks, the addition = 125x = 125 + 125 + ... + 125, x times. Thus, f(x) = 10 + 125x = 125x + 10.