There are 600 girls and 900 boys in an experimental primary school. How many boys are there? (using equation solution)
Suppose the number of boys is X
X-3*600=-900
X=3*600-900=900
A: the number of boys is 900
Suppose the number of boys is X
X-3*600=-900
X=3*600-900=900
A: the number of boys is 900