In a certain sequence of numbers, each term after the first is found by doubling and then adding $3$ to the previous term. if the seventh term of the sequence is $125$, what is the first term?

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x

b). 4320 have a nice day