Hint: These are the first letters of the words: A, C, D, D, I, L, M, N, P, R.
acq + uit + tal = acquittal
con + duc + tor = conductor
dec + kch + air = deckchair
dif + fer + ent = different
imp + ort + ant = important
lig + htn + ing = lightning
myt + hol + ogy = mythology
new + sag + ent = newsagent
pol + ice + man = policeman
rec + tan + gle = rectangle
Hint: The largest possible numbers could start with 6 and 8, therefore the first digit of the answer is 1.
E + E = E
O + O = E
E + O = O
To discuss individual letters it's easiest to represent the sum as:
A B C
D E F +
G H I J
The largest values for A and D are 6 and 8, which makes G = 1.
Since column 2 is E + O = O there can be no carry from column 1 (since E + O + 1 is always even). Therefore C and F are 3 and 5 (but we don't yet know which is which), therefore J = 8.
There can't be a carry from column 2 (as A + D is even) therefore E can't be 9 as this would force a carry.
Therefore I = 9. Hence B can't be 0. Therefore H = 0.
The last remaining odd number makes E = 7. Making B = 2.
Therefore A and D are 4 and 6 (but we don't yet know which is which).
Since the top row's digits have to add to 9 the top number must be 423.
This makes the sum 423 + 675 = 1098.