Sue drove 202 miles in April.
Explanation: To find the average, you would add up all the numbers and divide by the amount of numbers (4). Since there's a missing number that you need to find, you will basically do it backwards.
438 + 412 + 270 + X / 4 = 328
Multiply by 4 on both sides
438 + 412 + 270 + X = 1,312
Add up the miles from January, February, and March
1,120 + X = 1,312
Subtract 1,120 on both sides
X = 202