Answer:
40
Step-by-step explanation:
Subtracting a number k from 300 looks like this 300-k.
Adding a number k to 220 looks like this 220+k.
They are saying for some number k that we have 300-k and 220+k is the same value.
That is, 300-k=220+k.
This is the equation we are going to solve for your number.
300-k=220+k
Add k on both sides:
300=220+2k
Subtract 220 on both sides;
80=2k
Divide both sides by 2:
40=k
k=40.
So the number is 40.
Check: 300-40=260 while 220+40=260.
