Answer:
y = -1 and u = 3.333
Explanation:
The given equations are :
3u + y = 9 ...(1)
3u-5y = 15 ...(2)
Subtract equation (2) from (1).
3u + y-( 3u-5y)= 9 -15
y+5y = -6
6y = -6
y = -1
Put the value of y in equation (1).
3u + (-1) = 9
3u-1 = 9
3u = 10
u = 10/3
u = 3.333
The attached figure shows the graph for the above equations.