f is a trigonometric function of the form of a sin(bx+c) + d. Below is the graph f(x). The function intersects its midline at (3, -6.5) and has a maximum point at (4, - 2). Find a formula for f(x). Give an exact expression.​

Twenty-five percent of the customers entering a grocery store between 5 p.m. and 7 p.m. use an express checkout. consider five randomly selected customers, and let x denote the number among the five who use the express checkout.

How to solve a simultaneous equation involved with fractions?

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years