Question

The sum of three number is 15. If the second number is subtracted from the sum of first and third number then we get 5 an if twice of first number is added to second and if the third number is subtracted from the sum we get 4.

Answer 1

Let the three numbers be $a,b,c$

The sum of three numbers is $15$

$⟹a+b+c=15\cdots \left(1\right)$

The second number is subtracted from the sum of first and third number to geet $5$

$⟹a-b+c=5\cdots \left(2\right)$

twice of first number is added to second and if the third number is subtracted from sum we get $4$

$⟹2a+b-c=4\cdots \left(3\right)$

$\left(1\right)-\left(2\right)$

$⟹2b=10b=5$

put it in $\left(1\right)$

$⟹a+c=10c=10-a$

put it in $\left(3\right)$

$2a+5-10+a=43a-5=43a=9a=3⟹c=10-3c=7a=3;b=5;c=7$