Her estimate is lower than her actual cost because her total is 72.87 she is off by 1.72 because she only added 42,17,and 12 and forgot all about adding the cent or the .60,.38,and the .89.
It must end in a 0 for the number to be divisible by 10. The other 5 can go in any order, so 5 factorial (5!) = 5*4*3*2*1
120 numbers
It's a number that can be expressed as a fraction, the numerator and the denominator of which, are integers.
Here is my answer. In this problem, you need to use the similarity of triangles. I hope this is helpful.