(21+39a)/20. Because they have to have the same denominator
Answer:
Last one:
2 x + 4 y = 6. 3 x minus 4 y = 9.
Step-by-step explanation:
2x + 4y = 6
3x - 4y = 9
4y = 3x - 9
2x + 3x - 9 = 6
5x = 15
x = 3
4y = 3(3) - 9
4y = 0
y = 0
Only one solution, which is (3,0)
Answer:
When x=8, y=-6. When x=10, y=0
Step-by-step explanation:

You can plug the given y value into the second equation to get:

Hope this helps!
Answer:
x = 4
Step-by-step explanation:
DO + OB = DB
15 + 3x + 7 = 9x - 2
3x + 22 = 9x - 2
3x + 24 = 9x
24 = 6x
4 = x