Mrs. Cook is a teacher whose salary is $23,125 for a 185-day school year. In Mrs. Cook's school district, substitute teachers are paid at a rate of $90 per day. If a substitute is paid to teach Mrs. Cook's class in her absence one day, how much less does the school district pay in salary by paying a substitute teacher instead of paying Mrs. Cook for that day? *

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.