Question

2x+3y=5 and 7x-9y=-2 then find the value of 12x +15y

Answer 1

SOLUTION:-

Given, equation;

⚫2x +3y=5.........(1)

⚫7x -9y=-2....... (2)

From equation (1), we get;

➨2x +3y= 5

➨2x= 5-3y

➨x= 5-3y/2.......(3)

Therefore,

Putting the value of x in equation (2), we get;

$= > 7x - 9y = - 2 \\ \\ = > 7 \frac{(5 - 3y}{2} ) - 9y = - 2 \\ \\ = > \frac{35 - 21y}{2} - 9y = - 2 \\ \\ = > 35 - 21y - 18y = - 4 \\ \\ = > 35 - 39y = - 4 \\ \\ = > - 39y = - 4 - 35 \\ \\ = > - 39y = -39 \\ \\ = > y = \frac{ - 39}{ - 39} \\ \\ = > y = 1$

Eliminate the value of y in equation (3)* we get;

$x = \frac{5 - 3y}{2} \\ \\ = > \frac{5 - 3(1)}{2} \\ \\ = > \frac{5 - 3}{2} \\ \\ = > \frac{2}{2} \\ \\ = > 1$

Now,

The value of 12x+15y,

➨ 12(1) + 15(1)

➨ 12 + 15

➨ 27

Hope it helps ☺️