In a recent golf match, Desmond’s score was 3 less than George’s score. Their combined scores totaled 187. Let d represent Desmond's score and g represent George's score. Which pair of equations can be used to determine their scores?

Ad + g = 3

187 + d = g

Bd + g = 187

d – g = 3

Cd = g – 3

d + g = 187

Dg = d – 3

d + g = 187

please explain as well