If there are 1030 grains of sand on playa de sonrisa, how many of these grains of sand are submerged by the ocean at least once a day?

85 percent

Explanation:

(1) 40% of the grains of sand are submerged at least twice a day --> 0.4*1030 grains are submerged twice or more. Not sufficient,

(2) 55% of the grains of sand are not submerged exactly once a day. This imply that the remaining 45%, so 0.45*1030 grains, ARE submerged exactly once a day. Not sufficient.

(1)+(2) We have that 45% are submerged exactly once and 40% are submerged twice or more. Therefore, 45% + 40% = 85% are submerged at least once (once ore more). Sufficient.

the answer is:

c. islam and christianity

explanation:

islam and christianity are widely practiced in africa. islam is practiced due to its spread from the middle east into africa, and christianity is practiced due to the colonization of africa by the british empire.

your wrong the correct is d i did edunity and the answer