Question

Determine the value of x that is a solution to the following two equations:

7y - 15x = 61 ;

-x + 10y = 25

Answer 1

The system of equations are

7y - 15x = 61 ------------> (1)

-x + 10y = 25 --------------> (2)

Rewrite the Eq (2)

10y  =  25 + x 

y  =  ( 25 + x ) / 10

y  =  25/10 + x / 10

y  =  5/2 + x / 10

Substitute the value y  =  5/2 + x / 10 in Eq (1)

7(5/2 + x / 10) - 15x  =  61

35/2 + 7x/10 - 15x  =  61

(7x - 150x) /10  =  (122 - 35) / 2

-143x / 10  =  87 / 2

-143x  =  ( 87 / 2) 10

-143x  =  435

x  =  - 435/143

Answer :

The value of x  is  - 435/143.