Ahmad, Perry, Elijah and Riordan participated in a History quiz. The average number of points scored by Ahmad and Perry was 78. The average number of points scored by Perry and Riordan was 71.8. The average number of points scored by Ahmad, Perry and Riordan was 70. The average number of points scored by Elijah and Riordan was 69. How many points did each of them score?

1. Riordan
2. Ahmad
3. Perry
4. Elijah

(a)
Total score of Ahmad and Perry
= 78 x 2
= 156

Total score of Perry and Riordan
= 71.8 x 2
= 143.6

Total score of Ahmad, Perry and Riordan
= 70 x 3
= 210

Riordan's score
= 210 - 156
= 54

(b)
Ahmad's score
= 210 - 143.6
= 66.4

(c)
Perry's score
= 143.6 - 54
= 89.6

(d)
Total score of Elijah and Riordan
= 69 x 2
= 138

Elijah's score
= 138 - 54
= 84

Answer(s): (a) 54; (b) 66.4; (c) 89.6; (d) 84