Stupid problem that always shows up on UIL tests this year

[mathslug]

If A is 10% more than B and B is 10% less than C, then A is what % less than C?

or

A is 10% less than B and B is 20% more than C, A is what % more than C?

or

A is 2/3 of B and B is 3/4 of C. C is what % of A.

I always get confused in reading these questions. Has anyone divised a good algorithm for dealing with these on NS tests?

Zack

[bradp]

he seems to be giving them in the form

a = k1b and b = k2c (k1 and k2 are constants)
so substitute k2c in for b

multiply k1 and k2 which gives you a is x percent of c and go from there

a = 1.1b, b = .9 c
a = 1.1(.9)c
a = .99 c
1%