We have n dollars to spend. Every day we buy either a candy for 1 dollar or an ice cream for 2 dollars. In how many ways can we spend the money

P(n) = P(n - 1) + P(n - 2) where P(1) = 1 and P(2) = 2, 1, 2, 3, 5, 8, 13, 21, 34, ...

Step-by-step explanation:

If we suppose that the order of which they are bought matters, then we either buy candy or an ice cream last. In other words, we have (n - 1) or (n - 2) left on previous days to spend.

Therefore,

P(n) = P(n - 1) + P(n - 2)

Where P(1) = 1 and P(2) = 2,

1, 2, 3, 5, 8, 13, 21, 34, ...

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18