Answer:
x=19
Step-by-step explanation:
cross multiply
(−3)(+5)(3+5)=(−3)(+5)⋅2−3
(−3)⋅3=(+5)⋅2
3(−3)=(+5)⋅2
=19
10 students averaged 80, so the sum of their scores was (10 x 80) = 800
20 students averaged 89, so the sum of their scores was (20 x 89) = 1,780
All together, the sum of all 30 scores was (800 + 1,780) = 2,580
30 students totaled 2,580, so their average was (2,580 / 30) = <em> 86</em> .
Answer:
Step-by-step explanation:
im sry i dont know
