Question

John has a total of 10 blue, white and red marbles in his bag. If the number of blue marbles is 4 and the number of red marbles is 3, then the number of white marbles is

Answer 1

Let the number of white marbles be $w$
Given that total number of blue, red and white marbles in the bag is 10,
$4+w+3=10$
$\Rightarrow w=10-(4+3)=10-\left(7\right)=3$
$\therefore$ The number of white marbles is 3.