Need help answering and explaing these gre questions:

\f\f19. If y = 4x + 10 and y = 7x - 5, what is the value of y?27. x2 - 2x = 0 Quantity A Quantity B X 229. Quantity A Quantity B xy2z ( x2z + yz2 - xy2) x312z2 + xy323 - x24z 30\f\f41. xzy xy #0 Quantity A Quantity B - y + X+ - X42. If x + y = -3 and x2 + y2 = 12, what is the value of 2xy? 43. If x - y = 1/2 and x2 - y2 = 3, what is the value of x + y? 44. If x2 - 2xy = 84 and x - y = -10, what is the value of byl?45. ( x - 2) 2 + ( x - 1)2 + x2 + ( x + 1 ) 2 + ( x + 2) 2 = (A) 5x2 (B) 5x2 + 10 (C) x2 + 10 (D) 5x2 + 6x + 10 (E) 5x2 - 6x + 10 46. If a = (x + y)2 and b = x2 + y and xy > 0, which of the following must be true? Indicate all such statements. a = b a>b50. 3a + 2b = 20 and 2a + 3b = 5 Quantity A Quantity B atb a 51. m + 2n = 10 and m is 50% of n Quantity A Quantity B m2 n 52. For the integers a, b, and c, the sum of a and b is 75% of c. Quantity A Quantity B (3/4)(a + b) (4/3) (c)53. If 2a = 4b = 8c= 10, then 64abc= (A) 64,000 (B) 16,000 (C) 8,000 (D) 4,000 (E) 1,000 54. If 4m2 + 6n3 - 9 = 16, what is the value of 2m2 + 3n3? 55. If a + b = 8, b + c= 11, and a + c= 5, what is the value of a + b + c