We can figure this out using the explicit formula.

n represents the term we are looking for.
f(1) represents the first term in the sequence, which in this case, is 7.
d represents the common difference, which in this case, is +3.
f(n) = 7 + 3(n - 1)
f(n) = 7 + 3n - 3
f(n) = 4 + 3n
Now, we can input 214 for n and solve.
f(214) = 4 + 3(214)
f(214) = 4 + 642
f(214) = 646
The 214th term in this sequence is 646.
40+3+.04+.003
expanded form is showing what you have to add together
1. x <= 31
2. x < 28
For number 1, x is less than or equal to 31 because the number of days in a month (represented by x) will be less than or equal to 31.
For number 2, x is less than 28 because the number of students (represented by x) in each class will always be less than 28.
Here are some
1 ) 4 ( x - 3 )
2 ) 10 x - 2 x - 12
3 ) 8 x - 4 - 8