Question

Let P be a point between points S and T on 2004-01-01-02-00_files/i0120000.jpg. If ST = 21, SP = 3b – 11, and PT = b + 4, solve for b.

Answer 1

I got B as well

Explanation:

The person above already explained it.

Answer 2

Since P lies on the line ST, this means that the length of SP added to the length of PT will result in the length of ST
In other words:
length of SP + length of PT = length of ST
3b-11 + b+4 = 21
4b - 7 = 21
4b = 21+7
4b = 28
b = 28/4 = 7

Therefore:
SP = 3b-11 = 3(7)-11 = 21-11 = 10
PT = b+4 = 7+4 = 11