the sum of two times a number and 10 is the same as six times the difference of the number one and what is the number

The following division is being performed using multiplication by the reciprocal find the missing numbers is 5/12 divided by x/3 equals 5/12 times x/10 equals 1/x

Which of the following domains provide a real value periods

Find the amount of simple interest earned for depositing the given principle in an account if $2200 is invested at 5.5 % for 6 months