text: math: there are 250 students, girls number 20 less than twice number of boys. how many boys and girls?   boys=x girls=2x-20  add them together:  x+2x-20=250  combine like terms:  3x-20=250  add 20 to both sides:  3x=270  divide both sides by 3:  x=90  subtract 90 from 250 to get the number of girls, which is 160  hope this helps!