Answer: 3 kids take 3 pieces of candy each
Step-by-step explanation:
Let the number of children that took 3 pieces is x ( total take 3*x pieces of candy)
Number of children that took 5 pieces is y ( total take 5*y pieces of candy)
1 child took 1 piece that actually means that x+y=18 and 3*x+5*y=84.
( Because total number of all kids is 19. We just deduct one kid (Let his name is John) who took only 1 candy. So we have 19-1 =18 kids without John. The similar is with the candies. Total number is 85. We deduct 1 piece which John has taken. )
So we have 2 equations or the system of 2 equations:
1). x+y=18
2). 3*x +5*y=84
Multuply both sides of equation 1) by 3
We have 3*x+3*y=18*3
Deduct 3*y from both sides of this equation
3*x+3*y-3*y=54-3*y
3*x=54-3*y
Substitute 3*x in equation 2). by 54-3*y
2) 54-3*y+5*y=84
2*y=30
y=15 ( kids take 5 pieces of candy each)
Using equation 1) find x
x+15=18
x=3 (kids take 3 pieces of candy each)
