x-y=30 and x+5 = 2(y+5) | Simultaneous Equations | SciPiPupil

Question: Solve the pair of the following simultaneous equation: $x-y=30$ and $x+5=2(y+5)$.

Solution:

Given,

Equation (i) is $x-y = 30$

$or, x - 30 = y$

$or, y = x -30$

Equation (ii) is $x+5=2(y+5)$

Put value or y from equation (i) in equation (ii), we get,

$or, x + 5 = 2(x -30+5)$

$or, x + 5 = 2(x -25)$

$or, x + 5 = 2x -50$

$or, 50+5 = 2x -x$

$or, 55 = x$

$\therefore x = 55$

Now,

Put value of x in equation (i), we get,

$50 - y = 30$

$or, 50-30 = y$

$or, 20 = y$

$\therefore y = 20$

Hence, (x,y) = (55,20).

#SciPiPupil