Greg buys a school lunch for $1.50 each day. His caretaker gave him $40 for his lunches.
What equation represents how much money Greg has?
y = mx + b

For what values of b will f(x)= logbx be a decreasing function? (16 )

The variable z is directly proportional to x, and inversely proportional to y. when x is 4 and y is 13, z has the value 1.2307692307692. what is the value of z when x= 9, and y= 20

Lance lived in portugal and brazil for a total of 14 months to learn portuguese. he learned an average of 130 new words per month when he lived in portugal, and an average of 150 new words per month when he lived in brazil. in total he learned 1920 new words. write a system of equations to represent the situation. use x to represent portugal, and y to represent brazil