**Question 1**The forth term of a geometric progression is -20. The sum of the fourth and the fifth term is -16.

Find the first term and the common ratio of the progression.

[Note : Using Tn formula ${T}_{n}=a{r}^{n-1}$ to solve for

[Note : Using Tn formula ${T}_{n}=a{r}^{n-1}$ to solve for

*a*and*r*]

Solution:Solution: