Answer:
box contains - 3
Explanation:
a(x - 3) + 2x = -(x - 5) +4 Remove the brackets on both sides
ax - 3a + 2x = -x + 5 + 4 Subtract 2x from both sides.
ax - 3a + 2x - 2x = -x - 2x + 9
ax - 3a = - 3x + 9
ax - 3(-3) = - 3x + 9
ax + 9 = - 3x + 9
Now if you make a = -3 then both sides with have - 3 for the x coefficient.
Any number could be put in for x and it will make the answer on both sides equal. Notice you could subtract 9 from both sides and it will not change the condition of the problem.