1. $30; 20% markup

2. in math class there are 35 students. 2/5 of them have on a blue shirt. how many students don't have on a blue shirt?

To find the inverse of a number a, one can use the equation f(c) = a-1/c=0 where c is the inverse of a use the secant method of finding roots of equations to find the inverse of a = 2.5 ,er = 0.001%