Question

найдите X из пропорции X:4,2=1,5:2,1​

Answer 1

$\displaystyle \bf \Huge x:4,2=1,5:2,1;\\\\\bf \large \dfrac{x}{4,2}=\frac{1,5}{2,1}; \\\\\\\tt \huge 2,1x=4,2\cdot1,5;\\\\\\\sf \large 2,1x=6,3;\\\\\\\it \tiny x=6,3:2,1;\\\\\\\boxed{\Huge \rm x=3. }$