Today only a sofa is being sold at a 29% discount. the sale price is $639. what was the price yesterday?

What we need to do is find out what 29% of 639 is and add it to 639 to find the total.  The easiest way to find a percentage of a number, if you don't know how to calculate it, is by taking 10%.  So 10% of 639 is 63.9.  Now since there is 29%, we need to multiply 63.9 x 2, to get 127.8.  However, we only have 20% out of the 29%.  So we need to find the other 9%.  If 10% is 63.9, then 1% is 6.39.  So we need to multiply 6.39 x 9, and that equals 57.51.  Now, we need to add 127.80 and 57.51 together.  That will give us 185.31.  Add that to the 639, and you have your answer.  Hope this helped!

Ithink if im not mistaking b is -3 but im not a 100% sude