The table shows the number of minutes Jalen talks on his mobile phone and the cost of the phone calls.

Jalen’s Mobile Phone Cost
Number of minutes, x
150
220
250
275
Cost, y
$7.50
$11.00
$12.50
$13.75

If the cost varies directly with the number of minutes Jalen talks on the phone, which equation represents the variation?
y = 0.05 x
y = 20 x
y = 157.5 x
y = 1125 x