Nadia has 20 more postcards than Pete. After Nadia gives Pete some postcards, Pete has 2 more postcards than Nadia. How many postcards does Nadia give to Pete? 2.

11.

Step-by-step explanation:

N = Nadia.

P = Pete.

S = postcards that Nadia gives to Pete.

N = 20 + P

P + S = 2+N-S

To calculate S, we replaces N of the first equation in the second equation:

P + S = 2 + 20 + P-S

2S = 2 + 20 + P - P

2S = 22

S = 22/2 = 11.