<span>You need to set up 2 equations for this, a system to be exact
let x represent the cheaper phone and y represent the upgraded phone
for store costs you will have
5x+25y=200
for selling prices you will have 30x+100y=900
set these two equations together
5x+25y=200
30x+100y=900
multiply the first one by -4 and add them
-20x-100y=-800
30x+100y=900
10x=100
x=10
10 cheaper phones, plug into any equation again
5(10)+25(y)=200
y=6<<<6 upgraded phones</span>
I got B and D, sorry if my answers are wrong!!
If your turn 3/5 into 6/10 it becomes easier to turn into a decimal or a percentage.
3/5 = 0.60 = 60%
Hope this helps you finish your work!
