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> .
X=13; do you need the work? Also for future reference symbolab.com is where I get all my answers.
<span>Divide $380 by 20 and then multiply the result by 7. Its really not hard I promise I basically just gave you the answer</span>
[ 4(4) x 4(3) ] / 4(5)
= [4(4+3)] / 4(5)
= 4(7) / 4(5)
= 4(7-5)
= 4(2)
