Question

describe how you know what number to add to both sides of an equation containing subtraction.

Answer 1

Did they give you an example of an equation?

Answer 2

nope

Answer 3

Well, In an example of :

2x = - 2x + 4

Which number would you add to both sides to cancel out?

Answer 4

it depends on what number you want to move to the other side

using @wmckinely 's example

2x = - 2x + 4

if we wanted to move the -2x on the right side to the left side
we would have to negate it on the right side
this could be done by adding 2x to both sides
because -2x +2x =0

the result would look like
2x+2x = 4


now say we wanted to move the 2x on the left side to the right side

again we need to negate that term on the left side
and this can be done by adding -2x or subtracting 2x to both sides

the result will look like

0=-4x +4


or if we wanted to move the 4 from the right side to the left side
negating the 4 on the right side means we would have to subtract 4 to both sides

because 4 -4 =0

and the result would look like
-4 +2x=-2x

Answer 5

i don't need the answer anymore but thanks :)