Question

Katie and Pamela put some money into their money boxes every week. The amounts of money (y), in dollars, in their money boxes after certain amounts of time (x), in weeks, are shown by the equations below:

Katie
y = 30x + 20

Pamela
y = 20x + 90

After how many weeks will Katie and Pamela have the same amount of money in their money boxes, and what will that amount be?


A. 6 weeks, $150
B. 6 weeks, $230
C. 7 weeks, $150
D. 7 weeks, $230

Answer 1

this will be when the value of y is the same for both equations
so we can say
30x + 20 = 20x + 90

solve for x

Answer 2

70

Answer 3

30 - 20x = 90 - 20
10x = 70
x = ?

Answer 4

7

Answer 5

right
and how can you work out the amount of money after the 7 weeks

Answer 6

remember y = 2x + 90 is the amount of money saved in x weels
so for 7 weeks y = ?

Answer 7

how do i do the money part?

Answer 8

just replace the x in 20x + 90 and work it out
20*7 + 90 = ?

Answer 9

* replace the x by 7

Answer 10

$230

Answer 11

yes

Answer 12

D is the correct option

Answer 13

thanks

Answer 14

yw