Basically, you need to have a sum of numbers that add up to be 16 but multiply to be 40.
Factors of 40:
1*40
8*5
2*20
Factors of 16:
1*16
8*2
4*4
We know that 1*16 and 1*40 won't work, they won't add/multiply to be those.
So,
let's try:
8*5/8*2
8(5t-2)
to get that, you simply multiply 8 to 5 to get 40, and 8 to 2 to get -16.
Your Answer:
8(5t−2)