We have:
121×243÷174 of 285
= 23×411 ÷ 711 of 821 [Converting mixed to improper fraction]
According to BODMAS rule, we solve "of" first
=23×411÷711×821=23×411÷111×83=23×411÷1×811×3=23×411÷833=23×411×338=23×41×38=23×11×32=23×1×31×2=23×32=66=1[Of simplified][Reciprocal of 833 is 338][Division simplified][Multiplication simplified]
∴ The answer is 1