One half of the students in alex's science class are girls one third of the girls in the class have blonde hair if 10 girls do not have blonde hair how many students are in alex's science class?

Answer 1

Let's say that

s is the total number of students,

b is the number of boys,

g is the total number of girls,

n is the number of non-blonde girls, and

e is the number if blonde girls.

We know that

s = b + g,

b = g,

g = n + e,

e = g/3, and

n = 10.

Substituting for b in the first equation gives us

s = g + g = 2g

Then we substitute for n and e in the third equation and solve for g:

g = g/3 + 10

g - g/3 = 10

g - (1/3)g = 10

(2/3)g = 10

g = 10 x (3/2) = 15

Finally, solve for s:

s = 2g = 2 x 15 = 30