Solve the system of equations by elimination :
5X + 3Y = 19
2X + 4Y = 20

The correct answer is: x=8/7 and y=31/7

Complete step by step solution:
Let 5x + 3y = 19…(i)
and 2x + 4y = 20….(ii)
On multiplying (i) with 2, we get 2(5x + 3y = 19)
⇒10x + 6y = 38…(iii)
On multiplying (ii) with 5, we get 5(2x + 4y = 20)
⇒10x + 20y = 100…(iv)
Now, we have the coefficients of x in (iii) and (iv) to be the same.
On subtracting (iii) from (iv),
we get LHS to be 10x + 20y - (10x+ 6y) = 20y - 6y = 14y
and RHS to be 100 - 38 = 62
On equating LHS and RHS, we have 14y = 62

On substituting the value of y in (i), we get 

Hence we get 
Note: We can also solve these system of equations by making the coefficients of y
to be the same in both the equations