Question

Solve the pair of linear (simultaneous) equation by the method of elimination by substitution :
y = 4x - 7
16x - 5y = 25

Answer 1

y = 4x - 7                                      ....(1)
16x - 5y = 25                                ....(2)

y = 4x - 7
Putting this value of y in (2)
∴ 16x - 5 (4x - 7) = 25
∴ 16x - 20x + 35 = 25
∴ - 4x = - 10
∴ x = `5/2`

From (1)
y = `4(5/2) - 7`
⇒ y = 10 - 7
⇒ y = 3
Solution is x = `5/2` and y = 3.