Math question 40 points!

1. the sum of 5 consecutive odd integers is 2,555. what is the sum of the first, third, and last integer?

2. find the solution to the following system of linear equations.

y = −9x + 20
y = −9x +16

3. how many solutions exist for the system of equations given below?

3a + 4b = 20
12a = 80 − 16b

4. determine the value of x for the following system of equations.

3x + 4y = 70
8x - 3y = 9