Question

Antonia and Carla have the same percentage of green marbles in their bags of marbles. Antonia has 4 green green marbles and 16 total marbles. Carla has 10 green marbles. How many of Carlas marbles are not green?

Answer 1

Given that Antonia and Carla have the same percentage of marbles and Antonia has 4 green marbles out of 16 marbles , to calculate the number of marbles that Carla has that aren't green we proceed as follows;
let the total number of Carla's marbles be x;
the percentage of green marbles that Antonia has is:
4/16×100=25%

since they have the same percentage then:
number of green marbles Carla has is 10:
this is 25% of x, hence:
10/x×100=25
1000/x=25
1000=25x
thus
x=1000/25
x=40
Carla has a total of 40 marbles. Thus the number of marbles which are not green will be:
40-10=30 marbles