Question

Solve the pair of linear (simultaneous) equation by the method of elimination by substitution:
6x = 7y + 7
7y - x = 8

Answer 1

6x = 7y + 7                                  ...(1)
7y - x = 8                                     ...(2)

7y - x = 8
∴ x = 7y - 8

Putting this value of x in (1)
6( 7y - 8 ) = 7y + 7
∴ 42y - 48 = 7y + 7
∴ 35y = 55
∴ y = `11/7`

From (2) 
`x = 7(11/7) - 8`
x = 3

∴ x = 3, y = `11/7`.