Question

please please help me I don't know ​

Answer 1

Answer:

-3-(x) =18

- (x) = 18 +3

-(x) = 21

x = -21

therefore -21 should be subtracted from -3 to get +21

-3 -(-21)=

-3+21=18

Answer 2

Step-by-step explanation:

Let the unknown number be x.

Now,

(-3) - x = 18

(-3) = 18 + x

x = (-3) - 18

x = -21

Hence, the required Answer is-21