10 over 15 = c over 18 cross multiply 10 × 18 which is 180 and 15c then divide by 15 by both sides which 180 divded by 15 is c= 12
9 over r = 6 over 8 cross multiply 9×8 which is 72 then 6r divide it by 6 by both sides which 72 divided by 6 which is r= 12
