When adding fractions, you simply want to create a common denominator by using the Least Common Multiple (LCM) of the two fractions' denominator (bottom number). So, since the least common multiple of 10 and 30 is 30 (smallest number you can get by multiplying them by any number, in this case it was 10x3 and 30x1) multiply both parts of the fraction by whatever number you multiply by to get the LCM; since you multiply 10 by 3 to get the LCM of 30, multiply 7 by 3 also, so get 21. The new number is 21/30. For 11/30 you do not change the fraction since the denominator is already 30. Now, add the numerators to get 21+11=32. Keep the denominators the same. The answer is 32/30, or 1 2/30 when simplified, which simplifies to: 1 1/15
