Question

Solve the following simultaneous equations by the substitution method:
x + 3y= 5
7x - 8y = 6

Answer 1

The given equations are
x + 3y= 5       ....(i)
7x - 8y = 6    ....(ii)
Now, consider equation
x + 3y = 5
⇒ x = 5 - 3y   ....(iii)
Substituting the value of x in eqn. (ii), we get
7(5 - 3y) - 8y = 6
⇒ 35 - 21y - 8y = 6
⇒ 35 - 29y = 6
⇒ -29y = -29
⇒ y = 1
Putting the value of y in eqn. (ii), we get
x = 5 - 3(1)
= 5 - 3 = 2
Thus, the solution set is (2, 1).