30*(5+ 1)/(5- 1)
=30*6/4
=45 yuan
2. The decimal point of the number moves one place to the left, which is 2.25 less than the original number. What is the original number?
2.25/( 1-0. 1)
=2.25/0.9
=2.5
A pen is more expensive than a ballpoint pen, 6.6 yuan. It is known that the unit price of a ballpoint pen is 65438+ 0/4 (fraction) of a pen. What is the unit price of pens and ballpoint pens?
Unit price of ballpoint pen:
6.6/(4- 1)
=6.6/3
=2.2 yuan
Pen unit price
2.2*4
=8.8 yuan