System of Equations

Question

5a - 8b     =4

10a     + 42c =48

     16b + 28c = 28

Answer 1

a = 6/5 = 1.2

b = 1/4 = 0.25

c = 6/7

use matrix algebra or substitution and elimination

5a-8b = 4, multiply by 2

10a-16b =8 subtract from 2nd equation to eliminate a

10a+42c = 48

10a -16b = 8

16b+42c = 40 subtract the last equation

16b+28c =28

14c =12

c=12/14 = 6/7

16b = 28 -28(6/7) = 28-24 =4

b=4/16 = 1/4

5a -8(1/4) =4

5a =4+2 = 6

a =6/5