Question

Stevie has some marbles

Answer 1

Let the number of marbles Stevie has = x.

Given Freddie has twice as many marbles as Stevie

Number of marbles Freddie has = 2x.

Given Danny has 5 more marbles than Freddie .

Number of marbles Danny has = 2x+5.

In total they have 55 marbles

x+2x+2x+5=55

Adding like terms :

5x+5=55

Subtracting 5 both sides

5x=50

Dividing both sides by 5

x=10

Number of marbles Danny has = 2x+5=2(10)+5=20+5=25

Answer 2

Stevie has 25marbles
Freddie's has 25x2:50marbles
Danny has 50+5:55marbles