Rounding 547+326=to estimate the sum?

X+ y = 5 ; x - y =3 solve using linear combination

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? *

What is the measure of sty in oo below? 130 310 230 50