Solve the following equations by substitution method.

5x + 3y = 21; 2x – y = 4

[In substitution method, we have to find value of one variable in terms of the other variable from any one of the two given equations . Then, we will substitute this value in the other equation. By doing this, we will get a equation in one variable which can be solved easily]

5x + 3y = 21……(1)

2x – y = 4…….(2)

From eq(2)

2x – y = 4

⟹y = 2x – 4…..(3)

Substituting value of y in eq(1)

5x + 3y = 21

⇒ 5x + 3(2x – 4) = 21

⇒ 5x + 6x – 12 = 21

⇒ 11x = 33

⇒ x =

⇒ x = 3

From eq(3)

y = 2x – 4

⇒ y = 2×3 – 4

⇒ y = 2

Hence,

x = 3, y = 2