# How do you solve 3x+y=21 and x+y=1?

x=10; y= -9
$3 x + y = 21$ (1)
$x + y = 1$ (2)
Subtracting (2) from (1) we get $2 x = 20 \mathmr{and} x = 10$ $\mathmr{and} y = 1 - 10 = - 9 \left[A n s w e r\right]$