Forty-five children attend a preschool. the number of two-year-olds is one half the number of three-year-olds. the number of four-year-olds is the same as the number of 3-year-olds

Let x= the one you don' t have any information therefore x= 3 yr olds 1/2 x= 2 yr olds x= 4 yr. old x+1/2x+x=45 2x+1/2x=45 make the fraction a whole number by multiplying the equation by 2 4x+x=90 5x=90 x=18 # of 3yr olds 1/2(18)=9 # of 2 yr olds x=18. # of 4 yr olds