Can someone help me solve these questions i'm finding it really difficult.....

SIMULTANEOUS EQUATION

2x+y=7

3x-y=3

SOLVE ALGEBRAICALLY

(a) y= x^2 + 3x -8

y= x - 5

(b) Write down the formula to find the roots of the equation

(c) Use the formula to find the roots of: 3x^2-9x-16=0