Matt gives half of his books to the local library and kept the other half. his best friend gives him 3 more books. he now has 57 books. how many did he have to start.
this is a algebra question haves to have a main first equation

Can someone me with my hwplz(only the circled ones)

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)

The number of members f(x) in a local swimming club increased by 30% every year over a period of x years. the function below shows the relationship between f(x) and x: f(x) = 10(1.3)xwhich of the following graphs best represents the function? graph of f of x equals 1.3 multiplied by 10 to the power of x graph of exponential function going up from left to right in quadrant 1 through the point 0, 0 and continuing towards infinity graph of f of x equals 10 multiplied by 1.3 to the power of x graph of f of x equals 1.3 to the power of x