Please help! What's the difference between the two expressions? (3/7x+9)-(2/7x-3)

Plz hurry evaluate the expression a+b where a=8 and b=19

If t8 = 4 and t12 = −2, find the first three terms of the arithmetic sequence.

36x2 + 49y2 = 1,764 the foci are located at: a) (-√13, 0) and (√13,0) b) (0, -√13) and (0,√13) c) (-1, 0) and (1, 0)