For the arithmetic sequence
a₁, a₂, a₃, ...,
the n-th term is

where d = the common difference
Because a₅ = 12.4,
a₁ + 4d = 12.4 (1)
Because a₉ = 22.4,
a₁ + 8d = 22.4 (2)
Subtract (1) from (2).
a₁ + 8d - (a₁ + 4d) = 22.4 - 12.4
4d = 10
d = 2.5
From (1),
a₁ = 12.4 - 4*2.5 = 2.4
Therefore
a₃₁ = 2.4 + 30*2.5 = 77.4
Answer: a₃₁ = 77.4
Answer:
Step-by-step explanation:
I would use the zoom setting
Answer:
D: 7p - 4
Step-by-step explanation:
If we have 7 pizzas and each one is worth p 7p would equal the cost of all seven. Then subtract 4 from the total.
Let Mike sold M cars and Bill sold B cars.
Now both sold 640 cars in total, means M + B = 640,
also Mike sold 3 times as many as Bill, means M = 3*B. So our equations became,
M + B = 640, & M = 3*B, put value of M in terms of B.
3*B + B = 640, 4*B = 640,
B = 640/4, B = 160, as M = 3*B, M = 3*160 = 480.
So Mike sold 480 cars & Bill sold 160 cars.