Joy and Cullen put some money into their money boxes every week. The amount of money (y), in dollars, in their money boxes after a certain amount of time (x), i

Question

Joy and Cullen put some money into their money boxes every week. The amount of money (y), in dollars, in their money boxes after a certain amount of time (x), in weeks, is shown by the equations below:

Joy: y = 30x + 20
Cullen: y = 20x + 90

Answer 1

If you want to know when they will have the same amount of money then set the equations equal to each other and solve for x  

 

30x + 20 = 20x + 90

10x = 70

x = 7 weeks 

 

Check:  Joy has 30*7 + 20 = 210 + 20 = 230 after 7 weeks

           Cullen has 20*7 + 90 = 140 + 90 = 230 after 7 weeks