Monica bought some postage stamps she uses 10 stamps on letters and 5 and on postcards then her grandmother gives her 20 more stamps. she now has 35 stamps left how many stamps did monica originally have?

35-20+10+5=30 so she began with 30 stamps

Monica bought some postage stamps.
10 stamps on letters
5 and on postcards
Her grandmother gives her 20 more stamps
She now has 35 stamps left.
How many stamps did Monica originally have?

lets solve this:-

35 - 20 + 5 + 10 = 30

Monica had 30 stamps to began with!