I think 73 because:
First I did '1,000 + x = 2,450'
Then I got 'x = 1450'
But then 20 can't go into 1450
So I just add another 10 to 1450 an got 1460
1460/20 = 73!
Hope this helps an is correct!!!
18 - 4 - 2/7j - 6/7j + 5 =
18 - 4 + 5 - 2/7j - 6/7j=
19 - 8/7j
He put in 1 extra cup because the recipe only needed 3. 4-3=1.