Help please! I don’t know how to solve these types of problems...

a₅ = -43

Step-by-step explanation:

You can automate this with Excel.

In cell A1, type -7.

Then, in cell A2, type =, click A1 and type -9.

Next, drag the cell A2 down, until you pass A5.

if you want to do it by hand:

a₁ = -7

a₂ = a₁ - 9 = -7 - 9 = -16

a₃ = a₂ - 9 = -16 - 9 = -25

a₄ = a₃ - 9 = -25 - 9 = -34

a₅ = a₄ - 9 = -34 - 9 = -43

answer: 45