Question

(c) 7x + 3y = 42
21x + 9y = 42
simultaneous equations ​

Answer 1

Step-by-step explanation:

7x+3y=42 --------(1)

21x+9y=42---------(2)

x=42-3y/7---------(3)

subsituting (3) on (2)

21×(42-3y/7)+3y=42

882-63y/7 + 3y =42

882-63y/7+21y/7=42

882-63y+21y/7=42

882-42y=42×7

-42y = 294 - 882

y=-588/-42

y = 14