Substitution method-- ? !
what is the x-coordinate of the solution for the system of equations?

y - x = 9
10 + 2x = -2y

enter your answer in the box.

x=

What are the vertical asymptotes of the function f(x) =5x+5/x2 + x-2

Ateacher has $80 to buy workbooks. each work book cost $3. if she buys as many workbooks as possible, how much money does she have leftover? a) $2 b) $4 c) $6 d) $8

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.