A₁ = -8 This is the first term in an arithmetic sequence.
d = 3, the common difference
a(n) = a₁ + d(n-1)
a₇ = -8 + 3(7-1)
a₇ = -8 + 3(6)
a₇ = -8 + 18
a₇ = 10
To check:
a₁ = -8
a₂ = -8 + 3 = -5
a₃ = -5 + 3 = -2
a₄ = -2 + 3 = 1
a₅ = 1 + 3 = 4
a₆ = 4 + 3 = 7
a₇ = 7 + 3 = 10
Use b for bicycles b and t for tricycles.
We know that each bicycle has 2 wheels, and each tricycle has 3 wheels, and if the entire number of wheels is 57, that means the
equation would be: 2b + 3t = 57
We can "separate" b by calling it "25 - t" as an alternative,
2(25 - t) + 3t = 57, or
50 - 2t + 3t = 57,
or 50 + t = 57, so
t = 7 So there must be 18 bicycles and 7 tricycles.
CHECKING:You can check this out by multiplying 7 tricycles x 3 wheels, which is 21,
and 18 bicycles x 2 wheels, which is 36
36 + 21 = 57
Mount everest (Himalayas) and mount elbert (rocky mountains)
