Question

What number must be subtracted from $3$ to obtain $-4$?

Answer 1

To find the missing number $(?)$ in $3-?=-4$, we take the help of a number line.

We need to find out how many steps need to move towards left to reach at $-4$, if initially positioned at $3$, and that many steps denote the missing number $(?)$.

We first place a yellow circle at the initial postion $3$.


Now, to reach $-4$, we have to move $7$ steps towards left from $3$ as shown below.


So, the number $\underset{–}{7}$ must be subtracted from $3$ to obtain $-4$, i.e., $3-\underset{–}{7}=-4$.