260+(20x) =140+(30x)
x represents the number of months.
subtract 20x from both sides and subtract 140 from both sides
120=10x
divide each side by 10
12=x
So in 12 months, Jamal will have paid the same amount to both shops.
To check your answer, you plug in 12 for x.
260+20(12)=140+30(12)
260+240=140+360
500=500
Hope this helps.
