She has saved $30 which is three fifths of the total cost, how much is the total cost

$50

Step-by-step explanation:

3/5=30/x

x= The total cost

You can see that 3×10 multiplies to 30, so the total cost would be 5×10.

Total cost= 50

1.

for the graph, just plot the points in the table and draw a straight line through them. it is assumed that these graphs are of a linear shape.

slope: cost is the rise, weight is the run. take two sets of coordinates, like (2,12) and (4,16). calculate the slope:



point-slope form of a line is  , so using either one of the points from earlier with slope m = 2 and then converting to slope-intercept



we see from slope-intercept equation of the line that the y-intercept is 8.

2.

same procedure. slope is 2/5, y-int is 2, equation is  .

3. the y-intercept is 100 because at x=0, y=100. the y-axis is at x=0, so that intercepts the y-axis.
the slope is 5.
equation is 

4. the y-intercept is 375 because at x=0, y=375.
the slope is -10 ( )
equation is