Question

If x +4y=5 and 5x+6y=7,then 3x +5y =?

Answer 1

Answer:

x = 5 -4y        -------- 3

put the value of x in eq - 2

5(5-4y)+6y = 7

25-20y+ 6y=7

25-7 -14y = 0

18- 14y =0

y = -18/-14

y = 9/7

put the value of y in eq -3

x = 5- 4 *9/7

x = -1/7

ATQ

3(-1/7)+5(9/7) = ?

-3/7+45/7 = 42/7 = 6

3x + 5y = 6