Question

If a+2b+3c=20 and 2a+4b+c=25,then find the value of c?

Answer 1

a + 2b + 3c = 20 ----------[ 1 ]

2a + 4b + c = 25 ----------[ 2 ]

[ 1 ] x 2 :

2a + 4b + 6c = 40----------[ 3 ]

[ 3 ] - [ 2 ] :

5c = 15

c = 15 ÷ 5

c = 5

Answer: c = 5