There are 25 gold cards, none of them are multiples of 10 (because they are odd).
There are 5 silver cards that are multiples of 10 (10, 20, 30, 40, 50)
That's a total of 30 favorable outcomes out of 50 possible cards.
P(gold or multiple of 10) = 30/50 = 3/5
PART B:
There are 25 silver cards (even)
Of the gold cards (odd), there are 4 multiples of 7 {7, 21, 35, 49}
That's a total of 29 favorable outcomes out of 50 possible cards.
P(silver or multiple of 7) = 29/50