Julie has $3.10 in change in her pocket. if she has only 50 cent and 20 cent pieces and the total number of coins is 11, how many coins of each type does she have?

50 cent pieces = qty 3

              20 cent pieces = qty 8

Step-by-step explanation:

Let x represent the 50 cent pieces and y represent the 20 cent pieces.  Create a system of equations using the quantity as one equation and the value as the other equation.  Use elimination method to solve for one of the variables, then use substitution to solve for the other variable.

    x  +      y  = 11     →     -20(x     +      y  = 11)      →   -20x  - 20y  = -220

.50x + .20y = 3.10   →   100(.50x + .20y = 3.10)  →   50x + 20y =   310  

                                                                                   30x           =    90

                                                                                      x            =     3

x + y = 11

3 + y = 11

    y = 8

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value