Question

(5+5) + (5 + 6) + (5 + 7) + (5 + 8) + .... + (5 + 14) + (5 + 15)

Answer 1

Answer:

C: 55

Step-by-step explanation:

Rearrange the bracketed terms to:

(10 + 0) + (10 + 1) + (10 + 2) + ... + (10 + 10)

There are 11 brackets so we have (11 * 10) + (0 + 1 + 2 + ... + 10) =

(11 * 10) + 55