I also need help on these last 2(number 20 and 9)

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches.approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *

12 out of 30 people chose their favourite colour as blue caculate the angle you would use for blue on a pie chart

Solve the system of equations using the substitution method. {y=−3x+7x=−2y−16 enter your answers in the boxes.