Question

1. 3u+z=15
u+ 2z = 10​

Answer 1

Multiply the second equation by -3 in order to cancel out U

3u+z=15
-3(u+2z)=10

3u+z=15
-3u-6z=-30. Then u subtract those two equations

-5z=-15
Z=3

To solve for u, plug in the z in one of the equation (doesn’t matter which one)

3u+3=15
3u=12
U=4

Ur answer is
U=4. Z=3