The difference in the cost of the two plans after 18 months will be 240. The solution has been obtained using linear equations.
A linear equation has the highest degree of 1 possible. This indicates that there are no variables in a linear equation with exponents greater than 1. Such an equation on the graph forms a straight line.
According to the table, the companies increase the cost by an equal amount every month.
So, the linear equations for both the companies come out to be,
Company A: y=40+35x
Company B: y=10+50x
Therefore, after 18 months cost of both companies will be
Company A:
y=40+35(18)
y=40+630
y=670
Company B:
y=10+50(18)
y=10+900
y=910
The difference in the cost of the two plans after 18 months will be
910-670= 240
Hence, the difference in the cost of the two plans after 18 months will be 240.