Can some one hwelp me with this hurry

4. 15 + 4x = 6 + 5x
           -x = -9
            x = 9

5. Sally : x , Martha : y
x = 2 + y
x + y = 5.64
2 + y + y = 5.64
2y = 3.64
y = 1.82
Sally paid $1.82.

6. Bob : x , Tim  : y
x = y - 3
x + y =7.80
y - 3 + y = 7.80
2y = 10.80
y = 5.4
Bob spent $5.40.