9514 1404 393
Answer:
175
Step-by-step explanation:
Let g represent the number of girls. Then 280-g is the number of boys. Their ratio is ...
boys/girls = 3/5 = (280-g)/g
Clearing fractions gives ...
3g = 5(280 -g)
8g = 1400 . . . . eliminate parentheses, add 5g
g = 175 . . . . . . . divide by 8
There are 175 girls in the grade 3 classes at Domino Primary School.