There are 3/4 as many boys as girls in a class of fifth-graders if there are 35 students in the class how many a

Alright so turn 3/4 into a decimal.
3/4 =.75

We need to set up an equation. To do that are need to give boys and girls their own variables.

Girls= X

And since there is 3/4 as many boys
Boys=. 75X

Now we know the sum of boys and girls equals 35
X+.75X=35

X+.75X=1.75X
Now we have 1.75X=35

Divide by 1.75 and get
20=X

Now plug 20 into the equations got from before.
Boys =. 75*X = 20 *. 75 = 15
Girls = X =20

Your
15 boys
20 girls

You can check
20+15=35
15/20=3/4