Question

Stevie has some marbles.

Freddie has twice as many marbles as Stevie.
Danny has 5 more marbles than Freddie.
In total, they have 55 marbles.
How many marbles does Danny have?

Answer 1

Let's denote the number of Stevie's marbles as x, then Freddie has 2x marbles and Danny has 2x+5. In total, they have x+2x+2x+5 marbles that is equal to 55.
x+2x+2x+5=55, then 5x+5=55, and 5x=55-5.
5x=50, from where x=50÷5, so x=10.
Stevie has 10 marbles, Freddie has 2x=2×10=20 marbles and Danny has 2x+5=2×10+5=20+5=25 marbles.