Question

Solve the pair of linear (simultaneous) equation by the method of elimination by substitution :
2x - 3y = 7
5x + y= 9

Answer 1

2x - 3y = 7                                       ...(1)
5x + y = 9                                        ...(2)

5x + y = 9
∴ y = 9 - 5x                                     ...(3)
Putting this value of y in (1)
2x - 3 (9 - 5x) = 7
∴ 2x - 27 + 15x = 7
∴ 2x + 15x = 7 + 27
∴ 17x = 34
∴ x = 2
From (2)
y = 9 - 5(2) 
y = -1