Maria started with $10. she has been saving $3 dollars each week to buy a softball bat. the amount of money maria has depends on how many weeks she has been saving. which expression represents maria after x weeks? * a) f(x) = 10x + 3 b) f(x) = 3x + 10 c) f(x) = 10x - 3 d) f(x) = 3x - 10

The correct answer is b as she starts with 10 and keeps on added 3 dollars per week

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.